Form N-Q

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, DC 20549

FORM N-Q


QUARTERLY SCHEDULE OF PORTFOLIO HOLDINGS OF REGISTERED MANAGEMENT INVESTMENT COMPANY

Investment Company Act file number         811-6548         

        Nuveen Select Tax-Free Income Portfolio         
(Exact name of registrant as specified in charter)

Nuveen Investments
        333 West Wacker Drive, Chicago, Illinois 60606         

(Address of principal executive offices) (Zip code)


Kevin J. McCarthy Vice President and Secretary
        333 West Wacker Drive, Chicago, Illinois 60606         

(Name and address of agent for service)

Registrant's telephone number, including area code:         312-917-7700        

Date of fiscal year end:            3/31          

Date of reporting period:         6/30/08         

Form N-Q is to be used by management investment companies, other than small business investment companies registered on Form N-5 (§§ 239.24 and 274.5 of this chapter), to file reports with the Commission, not later than 60 days after the close of the first and third fiscal quarters, pursuant to rule 30b1-5 under the Investment Company Act of 1940 (17 CFR 270.30b1-5). The Commission may use the information provided on Form N-Q in its regulatory, disclosure review, inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-Q, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-Q unless the Form displays a currently valid Office of Management and Budget ("OMB") control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to the Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. § 3507.

Item 1. Schedule of Investments

    Portfolio of Investments (Unaudited)             
    Nuveen Select Tax-Free Income Portfolio (NXP)             
    June 30, 2008             
Principal        Optional Call         
Amount (000)    Description (1)    Provisions (2)    Ratings (3)    Value 

    Municipal Bonds – 98.1%             
    Alaska – 2.0%             
$          2,475    Alaska Municipal Bond Bank Authority, General Obligation Bonds, Series 2003E, 5.250%, 12/01/23    12/13 at 100.00    AA (4)   $   2,697,008 
     (Pre-refunded 12/01/13) – MBIA Insured             
2,500    Northern Tobacco Securitization Corporation, Alaska, Tobacco Settlement Asset-Backed Bonds,    6/14 at 100.00    Baa3    1,866,650 
     Series 2006A, 5.000%, 6/01/46             

4,975    Total Alaska            4,563,658 

    Arkansas – 0.3%             
5,915    Arkansas Development Finance Authority, Tobacco Settlement Revenue Bonds, Arkansas Cancer    No Opt. Call    Aa3    702,939 
     Research Center Project, Series 2006, 0.000%, 7/01/46 – AMBAC Insured             

    California – 5.0%             
2,000    Alameda Corridor Transportation Authority, California, Subordinate Lien Revenue Bonds, Series    10/17 at 100.00    AA    1,657,860 
     2004A, 0.000%, 10/01/25 – AMBAC Insured             
3,325    California Department of Water Resources, Power Supply Revenue Bonds, Series 2002A,    5/12 at 101.00    Aa3    3,633,593 
     6.000%, 5/01/14             
3,000    Golden State Tobacco Securitization Corporation, California, Tobacco Settlement Asset-Backed    6/13 at 100.00    AAA    3,401,190 
     Bonds, Series 2003A-1, 6.750%, 6/01/39 (Pre-refunded 6/01/13)             
1,130    Los Angeles Department of Water and Power, California, Waterworks Revenue Refunding Bonds,    7/11 at 100.00    AA    1,132,644 
     Series 2001A, 5.125%, 7/01/41 – FGIC Insured             
365    Los Angeles, California, Parking System Revenue Bonds, Series 1999A, 5.250%, 5/01/29 –    5/09 at 101.00    AA    367,066 
     AMBAC Insured             
1,000    Moreno Valley Unified School District, Riverside County, California, General Obligation Bonds,    No Opt. Call    AA    458,520 
     Series 2007, 0.000%, 8/01/23 – MBIA Insured             
750    Tobacco Securitization Authority of Northern California, Tobacco Settlement Asset-Backed    6/15 at 100.00    BBB    612,743 
     Bonds, Series 2005A-1, 5.500%, 6/01/45             
1,150    Woodside Elementary School District, San Mateo County, California, General Obligation Bonds,    No Opt. Call    AA+    343,908 
     Series 2007, 0.000%, 10/01/30 – AMBAC Insured             

12,720    Total California            11,607,524 

    Colorado – 11.5%             
1,700    Colorado Health Facilities Authority, Revenue Bonds, Catholic Health Initiatives, Series    3/12 at 100.00    AA (4)    1,792,650 
     2002A, 5.500%, 3/01/22 (ETM)             
690    Colorado Health Facilities Authority, Revenue Bonds, Catholic Health Initiatives, Series    3/12 at 100.00    AA (4)    742,571 
     2002A, 5.500%, 3/01/22 (Pre-refunded 3/01/12)             
390    Colorado Water Resources and Power Development Authority, Small Water Resources Revenue Bonds,    11/10 at 100.00    N/R    397,371 
     Series 2000A, 5.800%, 11/01/20 – FGIC Insured             
9,535    Denver City and County, Colorado, Airport System Revenue Bonds, Series 1991D, 7.750%, 11/15/13    No Opt. Call    A+    10,497,082 
     (Alternative Minimum Tax)             
5,000    Denver City and County, Colorado, Airport System Revenue Refunding Bonds, Series 2001A,    11/11 at 100.00    A+    5,047,150 
     5.625%, 11/15/17 – FGIC Insured (Alternative Minimum Tax)             
3,000    Denver Convention Center Hotel Authority, Colorado, Senior Revenue Bonds, Convention Center    12/13 at 100.00    N/R (4)    3,186,510 
     Hotel, Series 2003A, 5.000%, 12/01/23 (Pre-refunded 12/01/13) – XLCA Insured             
5,000    E-470 Public Highway Authority, Colorado, Senior Revenue Bonds, Series 2000B, 0.000%, 9/01/28    9/10 at 31.42    Aaa    1,470,250 
     (Pre-refunded 9/01/10) – MBIA Insured             
3,160    Northwest Parkway Public Highway Authority, Colorado, Revenue Bonds, Senior Series 2001A,    6/11 at 102.00    AA (4)    3,396,842 
     5.500%, 6/15/20 (Pre-refunded 6/15/11) – AMBAC Insured             

28,475    Total Colorado            26,530,426 

    District of Columbia – 0.6%             
1,000    District of Columbia, Hospital Revenue Refunding Bonds, Medlantic Healthcare Group, Series    8/08 at 100.00    AA (4)    1,003,960 
     1996A, 5.750%, 8/15/16 – MBIA Insured (ETM)             
60    District of Columbia, Revenue Bonds, Catholic University of America, Series 1999, 5.625%,    10/09 at 101.00    AAA    61,598 
     10/01/29 – AMBAC Insured             
205    District of Columbia, Revenue Bonds, Catholic University of America, Series 1999, 5.625%,    10/09 at 101.00    Aa3 (4)    215,498 
     10/01/29 (Pre-refunded 10/01/09) – AMBAC Insured             

1,265    Total District of Columbia            1,281,056 

    Florida – 4.4%             
10,000    JEA St. John’s River Power Park System, Florida, Revenue Refunding Bonds, Issue 2, Series    10/11 at 100.00    Aa2    10,338,600 
     2002-17, 5.000%, 10/01/17             

    Hawaii – 0.6%             
1,330    Hawaii, Certificates of Participation, Kapolei State Office Building, Series 1998A, 5.000%,    11/08 at 101.00    AA    1,352,224 
     5/01/17 – AMBAC Insured             

    Illinois – 13.8%             
1,965    Board of Trustees of Southern Illinois University, Housing and Auxiliary Facilities System    No Opt. Call    AA    1,104,802 
     Revenue Bonds, Series 1999A, 0.000%, 4/01/20 – MBIA Insured             
    Chicago Heights, Illinois, General Obligation Corporate Purpose Bonds, Series 1993:             
3,820     5.650%, 12/01/15 – FGIC Insured    12/08 at 100.00    N/R    3,865,420 
2,600     5.650%, 12/01/17 – FGIC Insured    12/08 at 100.00    N/R    2,630,914 
195    DuPage County Community School District 200, Wheaton, Illinois, General Obligation Bonds,    11/13 at 100.00    Aaa    205,362 
     Series 2003B, 5.250%, 11/01/20 – FSA Insured             
805    DuPage County Community School District 200, Wheaton, Illinois, General Obligation Bonds,    11/13 at 100.00    Aaa    876,339 
     Series 2003B, 5.250%, 11/01/20 (Pre-refunded 11/01/13) – FSA Insured             
600    Illinois Educational Facilities Authority, Student Housing Revenue Bonds, Educational    5/12 at 101.00    Aaa    661,542 
     Advancement Foundation Fund, University Center Project, Series 2002, 6.000%, 5/01/22             
     (Pre-refunded 5/01/12)             
525    Illinois Finance Authority, Revenue Bonds, Loyola University of Chicago, Tender Option Bond    7/17 at 100.00    AA    521,693 
     Trust 1137, 14.084%, 7/01/46 (IF)             
4,000    Illinois Finance Authority, Revenue Bonds, Northwestern Memorial Hospital, Series 2004A,    8/14 at 100.00    AA+ (4)    4,425,360 
     5.500%, 8/15/43 (Pre-refunded 8/15/14)             
1,320    Illinois Health Facilities Authority, Revenue Bonds, Decatur Memorial Hospital, Series 2001,    10/11 at 100.00    A    1,358,557 
     5.600%, 10/01/16             
2,700    Illinois Health Facilities Authority, Revenue Bonds, Lake Forest Hospital, Series 2002A,    7/12 at 100.00    A–    2,824,227 
     6.000%, 7/01/17             
2,275    Illinois Health Facilities Authority, Revenue Refunding Bonds, Elmhurst Memorial Healthcare,    1/13 at 100.00    Baa1    2,371,642 
     Series 2002, 6.250%, 1/01/17             
60    Illinois Health Facilities Authority, Revenue Refunding Bonds, Evangelical Hospitals    No Opt. Call    N/R (4)    61,826 
     Corporation, Series 1992B, 6.500%, 4/15/09 (ETM)             
3,125    Metropolitan Pier and Exposition Authority, Illinois, Revenue Bonds, McCormick Place Expansion    No Opt. Call    A1    2,083,281 
     Project, Series 1992A, 0.000%, 6/15/17 – FGIC Insured             
810    Metropolitan Pier and Exposition Authority, Illinois, Revenue Bonds, McCormick Place Expansion    No Opt. Call    AAA    255,725 
     Project, Series 2002A, 0.000%, 6/15/30 – MBIA Insured             
5,000    Metropolitan Pier and Exposition Authority, Illinois, Revenue Refunding Bonds, McCormick Place    6/12 at 101.00    AAA    5,138,950 
     Expansion Project, Series 2002B, 5.000%, 6/15/21 – MBIA Insured             
1,300    Schaumburg, Illinois, General Obligation Bonds, Series 2004B, 5.250%, 12/01/34 – FGIC Insured    12/14 at 100.00    AA+    1,324,037 
    Yorkville, Illinois, General Obligation Debt Certificates, Series 2003:             
1,000     5.000%, 12/15/19 (Pre-refunded 12/15/11) – RAAI Insured    12/11 at 100.00    A (4)    1,061,300 
1,000     5.000%, 12/15/20 (Pre-refunded 12/15/11) – RAAI Insured    12/11 at 100.00    A (4)    1,061,300 

33,100    Total Illinois            31,832,277 

    Indiana – 8.9%             
5,000    Duneland School Building Corporation, Indiana, First Mortgage Refunding Bonds, Series 1999,    2/09 at 101.00    AA    5,090,750 
     5.125%, 2/01/18 – MBIA Insured             
1,000    Franklin Community Multi-School Building Corporation, Marion County, Indiana, First Mortgage    7/14 at 100.00    A (4)    1,080,640 
     Revenue Bonds, Series 2004, 5.000%, 7/15/22 (Pre-refunded 7/15/14) – FGIC Insured             
2,000    Indiana Health Facility Financing Authority, Hospital Revenue Refunding Bonds, Columbus    No Opt. Call    AAA    2,258,480 
     Regional Hospital, Series 1993, 7.000%, 8/15/15 – FSA Insured             
1,000    Indiana Health Facility Financing Authority, Revenue Bonds, Community Foundation of Northwest    3/17 at 100.00    BBB–    887,150 
     Indiana, Series 2007, 5.500%, 3/01/37             
9,855    Indianapolis Local Public Improvement Bond Bank, Indiana, Waterworks Project, Series 2002A,    7/12 at 100.00    AA (4)    10,537,557 
     5.125%, 7/01/21 (Pre-refunded 7/01/12) – MBIA Insured             
750    West Clark 2000 School Building Corporation, Clark County, Indiana, First Mortgage Bonds,    1/15 at 100.00    AA    771,885 
     Series 2005, 5.000%, 7/15/22 – MBIA Insured             

19,605    Total Indiana            20,626,462 

    Iowa – 0.4%             
1,000    Iowa Tobacco Settlement Authority, Asset Backed Settlement Revenue Bonds, Series 2005C,    6/15 at 100.00    BBB    812,240 
     5.375%, 6/01/38             

    Kansas – 0.5%             
500    Lawrence, Kansas, Hospital Revenue Bonds, Lawrence Memorial Hospital, Series 2006,    7/16 at 100.00    A3    461,305 
     4.875%, 7/01/36             
750    Wamego, Kansas, Pollution Control Revenue Bonds, Kansas Gas and Electric Company, Series 2004,    6/14 at 100.00    AA    744,068 
     5.300%, 6/01/31 – MBIA Insured             

1,250    Total Kansas            1,205,373 

    Kentucky – 0.5%             
1,100    Jefferson County, Kentucky, Health System Revenue Bonds, Alliant Health System Inc., Series    10/08 at 101.00    AA (4)    1,115,158 
     1998, 5.125%, 10/01/18 – MBIA Insured (ETM)             

    Louisiana – 0.4%             
1,000    Tobacco Settlement Financing Corporation, Louisiana, Tobacco Settlement Asset-Backed Bonds,    5/11 at 101.00    BBB    930,880 
     Series 2001B, 5.875%, 5/15/39             

    Massachusetts – 1.0%             
500    Massachusetts Health and Educational Facilities Authority, Revenue Bonds, CareGroup Inc.,    7/18 at 100.00    A3    479,260 
     Series 2008E-1, 5.000%, 7/01/28             
20    Massachusetts Health and Educational Facilities Authority, Revenue Bonds, Partners HealthCare    7/11 at 101.00    AA    21,552 
     System Inc., Series 2001C, 6.000%, 7/01/17             
480    Massachusetts Health and Educational Facilities Authority, Revenue Bonds, Partners HealthCare    7/11 at 101.00    AAA    524,650 
     System Inc., Series 2001C, 6.000%, 7/01/17 (Pre-refunded 7/01/11)             
1,055    Massachusetts Turnpike Authority, Metropolitan Highway System Revenue Bonds, Senior Series    7/08 at 101.00    AA    1,037,677 
     1997A, 5.000%, 1/01/37 – MBIA Insured             
410    Massachusetts Turnpike Authority, Metropolitan Highway System Revenue Bonds, Subordinate    1/09 at 101.00    AA    398,746 
     Series 1999A, 5.000%, 1/01/39 – AMBAC Insured             

2,465    Total Massachusetts            2,461,885 

    Michigan – 1.7%             
1,000    Michigan State Hospital Finance Authority, Hospital Revenue Bonds, Detroit Medical Center    8/08 at 101.00    BB–    931,940 
     Obligated Group, Series 1998A, 5.125%, 8/15/18             
2,900    Michigan State Hospital Finance Authority, Hospital Revenue Refunding Bonds, Trinity Health    12/12 at 100.00    AA    2,939,092 
     Credit Group, Series 2002C, 5.375%, 12/01/30             

3,900    Total Michigan            3,871,032 

    Minnesota – 0.1%             
240    Minnesota Housing Finance Agency, Single Family Mortgage Revenue Bonds, Series 1995A,    7/08 at 101.00    AA+    242,450 
     5.200%, 1/01/17             

    Mississippi – 1.6%             
3,600    Calhoun County, Mississippi, Solid Waste Disposal Revenue Bonds, Weyerhauser Company Project,    10/08 at 102.00    BBB    3,660,480 
     Series 1992, 6.875%, 4/01/16 (Alternative Minimum Tax)             

    Missouri – 0.7%             
5,000    Kansas City Municipal Assistance Corporation, Missouri, Leasehold Revenue Bonds, Series    No Opt. Call    AA    1,549,100 
     2004B-1, 0.000%, 4/15/30 – AMBAC Insured             

    Nevada – 5.7%             
2,500    Clark County, Nevada, Motor Vehicle Fuel Tax Highway Improvement Revenue Bonds, Series 2003,    7/13 at 100.00    AA    2,556,550 
     5.000%, 7/01/23 – AMBAC Insured             
    Director of Nevada State Department of Business and Industry, Revenue Bonds, Las Vegas             
    Monorail Project, First Tier, Series 2000:             
2,360     0.000%, 1/01/21 – AMBAC Insured    No Opt. Call    AA    877,141 
4,070     0.000%, 1/01/22 – AMBAC Insured    No Opt. Call    AA    1,397,557 
6,025     5.375%, 1/01/40 – AMBAC Insured    1/10 at 100.00    AA    4,082,540 
1,515    Reno, Nevada, Capital Improvement Revenue Bonds, Series 2002, 5.500%, 6/01/21 – FGIC Insured    6/12 at 100.00    Baa1    1,531,286 
2,555    Reno, Nevada, Capital Improvement Revenue Bonds, Series 2002, 5.500%, 6/01/21 (Pre-refunded    6/12 at 100.00    Baa1 (4)    2,755,312 
     6/01/12) – FGIC Insured             

19,025    Total Nevada            13,200,386 

    New Hampshire – 0.1%             
380    New Hampshire Housing Finance Authority, Single Family Mortgage Acquisition Bonds, Series    5/11 at 100.00    Aa2    387,805 
     2001A, 5.600%, 7/01/21 (Alternative Minimum Tax)             

    New Jersey – 2.9%             
2,500    New Jersey Health Care Facilities Financing Authority, Revenue Bonds, Somerset Medical Center,    7/13 at 100.00    Ba2    2,235,150 
     Series 2003, 5.500%, 7/01/23             
    Tobacco Settlement Financing Corporation, New Jersey, Tobacco Settlement Asset-Backed Bonds,             
    Series 2002:             
1,460     5.750%, 6/01/32 (Pre-refunded 6/01/12)    6/12 at 100.00    AAA    1,554,462 
1,000     6.000%, 6/01/37 (Pre-refunded 6/01/12)    6/12 at 100.00    AAA    1,096,930 
2,500    Tobacco Settlement Financing Corporation, New Jersey, Tobacco Settlement Asset-Backed Bonds,    6/17 at 100.00    BBB    1,893,000 
     Series 2007-1A, 5.000%, 6/01/41             

7,460    Total New Jersey            6,779,542 

    New Mexico – 2.1%             
1,000    New Mexico Mortgage Finance Authority, Multifamily Housing Revenue Bonds, St Anthony, Series    9/17 at 100.00    AAA    936,810 
     2007A, 5.250%, 9/01/42 (Alternative Minimum Tax)             
4,000    University of New Mexico, FHA-Insured Mortgage Hospital Revenue Bonds, Series 2004, 4.625%,    7/14 at 100.00    AAA    3,937,520 
     7/01/25 – FSA Insured             

5,000    Total New Mexico            4,874,330 

    New York – 1.2%             
1,000    Dormitory Authority of the State of New York, FHA-Insured Mortgage Revenue Bonds, Kaleida    2/14 at 100.00    AAA    1,023,520 
     Health, Series 2004, 5.050%, 2/15/25             
1,215    Dormitory Authority of the State of New York, Revenue Bonds, Mount Sinai NYU Health Obligated    7/10 at 101.00    BBB+    1,259,153 
     Group, Series 2000A, 6.500%, 7/01/17             
385    Dormitory Authority of the State of New York, Revenue Bonds, Mount Sinai NYU Health Obligated    7/10 at 101.00    Baa1 (4)    416,316 
     Group, Series 2000A, 6.500%, 7/01/17 (Pre-refunded 7/01/10)             

2,600    Total New York            2,698,989 

    North Carolina – 1.2%             
2,195    North Carolina Eastern Municipal Power Agency, Power System Revenue Refunding Bonds, Series    7/08 at 100.00    Baa1    2,195,702 
     1993B, 5.500%, 1/01/21             
500    Raleigh Durham Airport Authority, North Carolina, Airport Revenue Bonds, Series 2001A, 5.250%,    5/11 at 101.00    Aa3    511,950 
     11/01/17 – FGIC Insured             

2,695    Total North Carolina            2,707,652 

    Ohio – 0.1%             
300    Lebanon, Ohio, Electric System Mortgage Revenue Bonds, Series 2001, 5.500%, 12/01/17    12/10 at 101.00    AA (4)    321,801 
     (Pre-refunded 12/01/10) – AMBAC Insured             

    Oklahoma – 2.1%             
1,000    Norman Regional Hospital Authority, Oklahoma, Hospital Revenue Bonds, Series 2005,    9/16 at 100.00    BBB    961,370 
     5.375%, 9/01/36             
4,000    Oklahoma Development Finance Authority, Revenue Bonds, St. John Health System, Series 2004,    2/14 at 100.00    AA–    3,999,760 
     5.000%, 2/15/24             

5,000    Total Oklahoma            4,961,130 

    Pennsylvania – 0.8%             
500    Pennsylvania Higher Educational Facilities Authority, Revenue Bonds, Widener University,    7/13 at 100.00    BBB+    499,395 
     Series 2003, 5.250%, 7/15/24             
700    Pennsylvania Turnpike Commission, Turnpike Revenue Bonds, Series 2004A, 5.500%, 12/01/31 –    12/14 at 100.00    AA    726,768 
     AMBAC Insured             
520    Pennsylvania, General Obligation Bonds, Second Series 2001, 5.000%, 9/15/20 (Pre-refunded    9/11 at 101.00    AAA    555,214 
     9/15/11) – FSA Insured             

1,720    Total Pennsylvania            1,781,377 

    South Carolina – 7.8%             
1,000    Dorchester County School District 2, South Carolina, Installment Purchase Revenue Bonds,    12/14 at 100.00    A    1,021,470 
     GROWTH, Series 2004, 5.250%, 12/01/20             
10,000    Greenville County School District, South Carolina, Installment Purchase Revenue Bonds, Series    12/12 at 101.00    AA– (4)    11,105,699 
     2002, 5.875%, 12/01/19 (Pre-refunded 12/01/12)             
1,500    Lexington County Health Service District, South Carolina, Hospital Revenue Refunding and    11/13 at 100.00    A+ (4)    1,664,205 
     Improvement Bonds, Series 2003, 6.000%, 11/01/18 (Pre-refunded 11/01/13)             
520    South Carolina JOBS Economic Development Authority, Economic Development Revenue Bonds, Bon    11/12 at 100.00    A– (4)    567,304 
     Secours Health System Inc., Series 2002A, 5.625%, 11/15/30 (Pre-refunded 11/15/12)             
1,980    South Carolina JOBS Economic Development Authority, Economic Development Revenue Bonds, Bon    11/12 at 100.00    A–    1,994,711 
     Secours Health System Inc., Series 2002B, 5.625%, 11/15/30             
1,670    Tobacco Settlement Revenue Management Authority, South Carolina, Tobacco Settlement    5/11 at 101.00    BBB    1,762,167 
     Asset-Backed Bonds, Series 2001B, 6.000%, 5/15/22             

16,670    Total South Carolina            18,115,556 

    Texas – 9.7%             
5,000    Brazos River Harbor Navigation District, Brazoria County, Texas, Environmental Facilities Revenue    5/12 at 101.00    A–    5,065,400 
     Bonds, Dow Chemical Company Project, Series 2002A-6, 6.250%, 5/15/33 (Mandatory put             
     5/15/17) (Alternative Minimum Tax)             
1,000    Dallas Area Rapid Transit, Texas, Senior Lien Sales Tax Revenue Bonds, Series 2001, 5.000%,    12/11 at 100.00    AAA    1,060,870 
     12/01/31 (Pre-refunded 12/01/11) – AMBAC Insured             
6,150    Dallas Independent School District, Dallas County, Texas, General Obligation Refunding Bonds,    2/12 at 100.00    AAA    6,403,565 
     Series 2002, 5.250%, 2/15/20             
360    Dallas-Fort Worth International Airport Public Facility Corporation, Texas, Airport Hotel    1/09 at 100.00    AAA    364,028 
     Revenue Bonds, Series 2001, 5.500%, 1/15/20 – FSA Insured             
2,300    Harris County Health Facilities Development Corporation, Texas, Thermal Utility Revenue Bonds,    11/13 at 100.00    AA    2,278,472 
     TECO Project, Series 2003, 5.000%, 11/15/30 – MBIA Insured             
3,470    Harris County-Houston Sports Authority, Texas, Senior Lien Revenue Refunding Bonds, Series    11/30 at 61.17    AA    539,065 
     2001A, 0.000%, 11/15/38 – MBIA Insured             
2,585    Harris County-Houston Sports Authority, Texas, Third Lien Revenue Bonds, Series 2004-A3.,    11/24 at 52.47    AA    484,093 
     0.000%, 11/15/35 – MBIA Insured             
45    Irving Independent School District, Dallas County, Texas, General Obligation Refunding Bonds,    2/12 at 100.00    AAA    44,877 
     Series 2002A, 5.000%, 2/15/31             
3,455    Irving Independent School District, Dallas County, Texas, General Obligation Refunding Bonds,    2/12 at 100.00    AAA    3,661,885 
     Series 2002A, 5.000%, 2/15/31 (Pre-refunded 2/15/12)             
1,780    Leander Independent School District, Williamson and Travis Counties, Texas, General Obligation    8/16 at 35.23    AAA    347,331 
     Bonds, Series 2007, 0.000%, 8/15/37             
465    San Antonio, Texas, Water System Revenue Refunding Bonds, Series 1992, 6.000%, 5/15/16    5/12 at 100.00    AAA    511,095 
     (Pre-refunded 5/15/12) – MBIA Insured             
1,750    Texas, General Obligation Bonds, Water Financial Assistance Program, Series 2003A, 5.125%,    8/13 at 100.00    Aa1    1,663,025 
     8/01/42 (Alternative Minimum Tax)             

28,360    Total Texas            22,423,706 

    Utah – 0.4%             
775    Utah State Building Ownership Authority, Lease Revenue Bonds, State Facilities Master Lease    11/11 at 100.00    AA+    810,743 
     Program, Series 2001B, 5.250%, 5/15/24             

    Washington – 7.9%             
250    Energy Northwest, Washington, Electric Revenue Refunding Bonds, Columbia Generating Station –    7/12 at 100.00    Aaa    264,835 
     Nuclear Project 2, Series 2002C, 5.500%, 7/01/17 – MBIA Insured             
4,750    Snohomish County Public Utility District 1, Washington, Generation System Revenue Bonds,    No Opt. Call    Aaa    5,089,768 
     Series 1989, 6.750%, 1/01/12 (ETM)             
9,750    Washington State Healthcare Facilities Authority, Revenue Bonds, Sisters of Providence Health    10/11 at 100.00    AA    9,968,205 
     System, Series 2001A, 5.125%, 10/01/17 – MBIA Insured             
2,250    Washington State Tobacco Settlement Authority, Tobacco Settlement Asset-Backed Revenue Bonds,    6/13 at 100.00    BBB    2,278,103 
     Series 2002, 6.500%, 6/01/26             
2,115    Washington State, Motor Vehicle Fuel Tax General Obligation Bonds, Series 2003F, 0.000%,    No Opt. Call    AA+    771,658 
     12/01/27 – MBIA Insured             

19,115    Total Washington            18,372,569 

    West Virginia – 0.5%             
1,075    Marshall County, West Virginia, Special Obligation Refunding Bonds, Series 1992, 6.500%,    No Opt. Call    AAA    1,133,222 
     5/15/10 (ETM)             

    Wisconsin – 1.6%             
285    Badger Tobacco Asset Securitization Corporation, Wisconsin, Tobacco Settlement Asset-Backed    6/12 at 100.00    BBB    281,497 
1,000    Wisconsin Health and Educational Facilities Authority, Revenue Bonds, Wheaton Franciscan    8/13 at 100.00    A–    990,750 
     Services Inc., Series 2003A, 5.500%, 8/15/17             
2,500    Wisconsin, General Obligation Refunding Bonds, Series 2003-3, 5.000%, 11/01/26    11/13 at 100.00    AA–    2,544,325 

3,785    Total Wisconsin            3,816,572 

$       250,900    Total Municipal Bonds (cost $223,233,394)            227,069,144 


Shares    Description (1)            Value 

    Common Stocks – 0.0%             
    Airlines – 0.0%             
789    UAL Corporation, (5)          $  4,119 

    Total Common Stocks (cost $0)            4,119 

    Total Investments (cost $223,233,394) – 98.1%            227,073,263 

    Other Assets Less Liabilities – 1.9%            4,292,952 

    Net Assets – 100%          $  231,366,215 



(1)    All percentages shown in the Portfolio of Investments are based on net assets. 
(2)    Optional Call Provisions: Dates (month and year) and prices of the earliest optional call or redemption. There 
    may be other call provisions at varying prices at later dates. Certain mortgage-backed securities may be 
    subject to periodic principal paydowns. 
(3)    Ratings: Using the higher of Standard & Poor’s Group (“Standard & Poor’s”) or Moody’s Investor Service, Inc. 
    (“Moody’s”) rating. Ratings below BBB by Standard & Poor’s or Baa by Moody’s are considered to be 
    below investment grade. 
    The Portfolio of Investments may reflect the ratings on certain bonds insured by ACA, AMBAC, CIFG, FGIC, 
    MBIA, RAAI and XLCA as of June 30, 2008. Subsequent to June 30, 2008, and during the period this 
    Portfolio of Investments was prepared, there may have been reductions to the ratings of certain bonds 
    resulting from changes to the ratings of the underlying insurers both during the period and after period 
    end. Such reductions would likely reduce the effective rating of many of the bonds insured by that insurer 
    or insurers presented at period end. 
(4)    Backed by an escrow or trust containing sufficient U.S. Government or U.S. Government agency securities 
    which ensure the timely payment of principal and interest. Such investments are normally considered to be 
    equivalent to AAA rated securities. 
(5)    On December 9, 2002, UAL Corporation (“UAL”), the holding company of United Air Lines, Inc. (“United”) 
    filed for federal bankruptcy protection. The Adviser determined that it was likely that United would not 
    remain current on their interest payment obligations with respect to the bonds previously held and thus 
    the Fund had stopped accruing interest on its UAL bonds. On February 1, 2006, UAL emerged from federal 
    bankruptcy with the acceptance of its reorganization plan by the bankruptcy court. Under the settlement 
    agreement established to meet UAL’s unsecured bond obligations, the bondholders, including the Fund, 
    received three distributions of UAL common stock over the subsequent months, and the bankruptcy court 
    dismissed all unsecured claims of bondholders, including those of the Fund. On May 5, 2006, the Fund 
    liquidated such UAL common stock holdings. On September 29, 2006 and May 30, 2007, the Fund 
    received additional distributions of 1,901 and 617 shares, respectively, of UAL common stock as a result 
    of its earlier ownership of the UAL bonds. The Fund liquidated the 1,901 shares of such UAL common 
    stock holdings on November 15, 2006. The Fund received an additional distribution of 172 UAL common 
    stock shares on November 14, 2007. The remaining 789 shares of UAL common stock were still held by 
    the Fund at June 30, 2008. 
N/R    Not rated. 
(ETM)    Escrowed to maturity. 
(IF)    Inverse floating rate investment. 

Fair Value Measurements

During the current fiscal period, the Fund adopted the provisions of Statement of Financial Accounting Standards No. 157, Fair Value Measurements (SFAS 157). SFAS 157 defines fair value, establishes a framework for measuring fair value in generally accepted accounting principles, and expands disclosure about fair value measurements. In determining the value of the Fund’s investments various inputs are used. These inputs are summarized in the three broad levels listed below:

Level 1 – Quoted prices in active markets for identical securities. 
Level 2 – Other significant observable inputs (including quoted prices for similar securities, interest 
              rates, prepayment speeds, credit risk, etc.). 
Level 3 – Significant unobservable inputs (including management’s assumptions in determining the 
              fair value of investments). 

The inputs or methodology used for valuing securities are not an indication of the risk associated with investing in those securities.

The following is a summary of the Fund’s fair value measurements as of June 30, 2008:

    Level 1    Level 2    Level 3    Total 

Investments    $4,119    $227,069,144    $—    $227,073,263 


Income Tax Information

The following information is presented on an income tax basis. Differences between amounts for financial statement and federal income tax purposes are primarily due to timing differences in recognizing taxable market discount, timing differences in recognizing certain gains and losses on investment transactions and the treatment of investments in inverse floating rate transactions subject to SFAS No. 140. To the extent that differences arise that are permanent in nature, such amounts are reclassified within the capital accounts on the Statement of Assets and Liabilities presented in the annual report, based on their federal tax basis treatment; temporary differences do not require reclassification. Temporary and permanent differences do not impact the net asset value of the Fund.

At June 30, 2008, the cost of investments was $222,736,039.

Gross unrealized appreciation and gross unrealized depreciation of investments at June 30, 2008, were as follows:


Gross unrealized:     
  Appreciation    $ 9,576,574 
  Depreciation    (5,239,350)

Net unrealized appreciation (depreciation) of investments    $ 4,337,224 



Item 2. Controls and Procedures.

  1. The registrant's principal executive and principal financial officers, or persons performing similar functions, have concluded that the registrant's disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940, as amended (the "1940 Act") (17 CFR 270.30a-3(c))) are effective, as of a date within 90 days of the filing date of this report that includes the disclosure required by this paragraph, based on their evaluation of the controls and procedures required by Rule 30a-3(b) under the 1940 Act (17 CFR 270.30a-3(b)) and Rule 13a-15(b) or 15d-15(b) under the Securities Exchange Act of 1934 (17 CFR 240.13a-15(b) or 240.15d-15(b)).
  2. There were no changes in the registrant's internal control over financial reporting (as defined in Rule 30a-3(d) under the 1940 Act (17 CFR 270.30a-3(d)) that occurred during the registrant's last fiscal quarter that have materially affected, or are reasonably likely to materially affect, the registrant's internal control over financial reporting.

Item 3. Exhibits.

File as exhibits as part of this Form a separate certification for each principal executive officer and principal financial officer of the registrant as required by Rule 30a-2(a) under the 1940 Act (17 CFR 270.30a-2(a)), exactly as set forth below: See EX-99 CERT attached hereto.


SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

(Registrant)         Nuveen Select Tax-Free Income Portfolio         

By (Signature and Title)          /s/ Kevin J. McCarthy                    
                                                  Kevin J. McCarthy
                                                  Vice President and Secretary

Date         August 29, 2008        

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

By (Signature and Title)         /s/ Gifford R. Zimmerman                    
                                                 Gifford R. Zimmerman
                                                 Chief Administrative Officer (principal executive officer) 

Date         August 29, 2008        

By (Signature and Title)         /s/ Stephen D. Foy                              
                                                 Stephen D. Foy
                                                 Vice President and Controller (principal financial officer) 

Date        August 29, 2008