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         811-6623         

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


        333 West Wacker Drive, Chicago, Illinois 60606         
(Address of principal executive offices) (Zip code)


Jessica R. Droeger—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:            03/31          

Date of reporting period:          06/30/05         

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 California Select Tax-Free Income Portfolio (NXC)             
                       June 30, 2005             
 
 
 
 
Principal            Optional Call        Market 
Amount (000)        Description    Provisions*    Ratings**    Value 
 
        Consumer Staples - 1.9%             
 
$ 1,740        California County Tobacco Securitization Agency, Tobacco Settlement Asset-Backed Revenue Bonds,    6/12 at 100.00    BBB    $ 1,755,782 
        Fresno County Tobacco Funding Corporation, Series 2002, 5.625%, 6/01/23             
 
        Education and Civic Organizations - 13.0%             
 
1,000        California Educational Facilities Authority, Revenue Bonds, Stanford University, Series 1999P,    12/09 at 101.00    AAA    1,072,070 
        5.000%, 12/01/23             
 
2,600        California Educational Facilities Authority, Revenue Bonds, University of the Pacific, Series 2002,    11/11 at 100.00    A2    2,761,486 
        5.250%, 11/01/21             
 
1,000        California Educational Facilities Authority, Revenue Bonds, University of San Diego, Series 2002A,    10/12 at 100.00    A2    1,078,540 
        5.500%, 10/01/32             
 
3,000        California Infrastructure Economic Development Bank, Revenue Bonds, J. David Gladstone Institutes,    10/11 at 101.00    A-    3,238,020 
        Series 2001, 5.500%, 10/01/19             
 
2,000        California State Public Works Board, Lease Revenue Bonds, University of California System, Series    10/12 at 100.00    AAA    2,125,360 
        2002A, 5.000%, 10/01/22 - FSA Insured             
 
750        California Statewide Community Development Authority, Student Housing Revenue Bonds, EAH - Irvine    8/12 at 100.00    A    796,448 
        East Campus Apartments, LLC Project, Series 2002A, 5.500%, 8/01/22 - ACA Insured             
 
1,000        Long Beach Bond Financing Authority, California, Lease Revenue Refunding Bonds, Long Beach Aquarium    11/11 at 101.00    AAA    1,074,460 
        of the South Pacific, Series 2001, 5.250%, 11/01/30 - AMBAC Insured             
 
        Healthcare - 8.9%             
 
2,000        California Infrastructure Economic Development Bank, Revenue Bonds, Kaiser Hospital Assistance LLC,    8/11 at 102.00    A+    2,149,140 
        Series 2001A, 5.550%, 8/01/31             
 
90        California Statewide Community Development Authority, Revenue Bonds, Daughters of Charity Health    7/15 at 100.00    BBB+    96,024 
        System, Series 2005A, 5.250%, 7/01/24             
 
1,880        California Statewide Community Development Authority, Revenue Bonds, Los Angeles Orthopaedic    6/07 at 101.00    AAA    1,984,302 
        Hospital Foundation, Series 2000, 5.500%, 6/01/17 - AMBAC Insured             
 
1,500        California Statewide Community Development Authority, Insured Mortgage Hospital Revenue Bonds,    11/09 at 102.00    A    1,592,010 
        Mission Community Hospital, Series 2001, 5.375%, 11/01/26             
 
1,500        California Statewide Community Development Authority, Hospital Revenue Bonds, Monterey Peninsula    6/13 at 100.00    AAA    1,645,890 
        Hospital, Series 2003B, 5.250%, 6/01/18 - FSA Insured             
 
790        Central California Joint Powers Health Finance Authority, Certificates of Participation, Community    8/05 at 100.00    Baa2    790,087 
        Hospitals of Central California, Series 1993, 5.000%, 2/01/23             
 
        Industrials - 1.4%             
 
1,250        California Pollution Control Financing Authority, Solid Waste Disposal Revenue Bonds, Republic    No Opt. Call    BBB+    1,325,563 
        Services Inc., Series 2002C, 5.250%, 6/01/23 (Alternative Minimum Tax) (Mandatory put 12/01/17)             
 
        Long-Term Care - 1.7%             
 
1,500        ABAG Finance Authority for Non-Profit Corporations, California, Insured Senior Living Revenue    11/12 at 100.00    A    1,592,940 
        Bonds, Odd Fellows Home of California, Series 2003A, 5.200%, 11/15/22             
 
        Tax Obligation/General - 21.9%             
 
        California, General Obligation Bonds, Series 2003:             
500        5.250%, 11/01/19 - RAAI Insured    11/13 at 100.00    AA    546,130 
1,450        5.250%, 2/01/21    8/13 at 100.00    A    1,595,247 
1,000        5.250%, 2/01/22 - CIFG Insured    8/13 at 100.00    AAA    1,085,960 
 
        California, General Obligation Bonds, Series 2004:             
750        5.000%, 2/01/23    2/14 at 100.00    A    796,462 
800        5.125%, 4/01/25    4/14 at 100.00    A    856,400 
 
2,000        Fremont Unified School District, Alameda County, California, General Obligation Bonds, Series    8/12 at 101.00    AAA    2,183,320 
        2002A, 5.000%, 8/01/21 - FGIC Insured             
 
        Golden West Schools Financing Authority, California, General Obligation Revenue Refunding Bonds,             
        School District Program, Series 1999A:             
4,650        0.000%, 8/01/16 - MBIA Insured    No Opt. Call    AAA    2,968,374 
1,750        0.000%, 2/01/17 - MBIA Insured    No Opt. Call    AAA    1,082,393 
2,375        0.000%, 8/01/17 - MBIA Insured    No Opt. Call    AAA    1,438,823 
2,345        0.000%, 2/01/18 - MBIA Insured    No Opt. Call    AAA    1,377,828 
 
395        Los Angeles Community College District, Los Angeles County, California, General Obligation Bonds,    8/15 at 100.00    AAA    425,636 
        Series 2005A, 5.000%, 6/01/26 - FSA Insured             
 
        Mountain View-Los Altos Union High School District, Santa Clara County, California, General             
        Obligation Capital Appreciation Bonds, Series 1995C:             
1,015        0.000%, 5/01/17 - MBIA Insured    No Opt. Call    AAA    621,312 
1,080        0.000%, 5/01/18 - MBIA Insured    No Opt. Call    AAA    627,901 
 
1,500        San Diego Unified School District, San Diego County, California, General Obligation Bonds, Series    7/13 at 101.00    AAA    1,690,410 
        2003E, 5.250%, 7/01/24 - FSA Insured             
 
        San Jose-Evergreen Community College District, Santa Clara County, California, General Obligation             
        Bonds, Series 2005A:             
100        5.000%, 9/01/25 - MBIA Insured    9/15 at 100.00    AAA    107,892 
150        5.000%, 9/01/27 - MBIA Insured    9/15 at 100.00    AAA    161,838 
 
2,565        Sunnyvale School District, Santa Clara County, California, General Obligation Bonds, Series 2005A,    9/15 at 100.00    AAA    2,769,661 
        5.000%, 9/01/26 - FSA Insured             
 
        Tax Obligation/Limited - 14.8%             
 
1,000        Bell Community Redevelopment Agency, California, Tax Allocation Bonds, Bell Project Area, Series    10/13 at 100.00    AA    1,090,440 
        2003, 5.625%, 10/01/33 - RAAI Insured             
 
        California, Economic Recovery Revenue Bonds, Series 2004A:             
1,250        5.000%, 7/01/15    7/14 at 100.00    AA-    1,385,075 
1,000        5.000%, 7/01/16    7/11 at 100.00    AA-    1,083,680 
 
1,000        California State Public Works Board, Lease Revenue Bonds, Department of Mental Health, Coalinga    6/14 at 100.00    A-    1,109,580 
        State Hospital, Series 2004A, 5.500%, 6/01/23             
 
3,500        California State Public Works Board, Lease Revenue Bonds, Department of Corrections, Calipatria    No Opt. Call    AAA    4,321,800 
        State Prison, Series 1991A, 6.500%, 9/01/17 - MBIA Insured             
 
1,400        Golden State Tobacco Securitization Corporation, California, Enhanced Tobacco Settlement    6/13 at 100.00    A-    1,547,798 
        Asset-Backed Bonds, Series 2003B, 5.500%, 6/01/33             
 
90        Hesperia Community Redevelopment Agency, California, Tax Allocation Bonds, Series 2005A, 5.000%,    9/15 at 100.00    AAA    97,572 
        9/01/20 - XLCA Insured             
 
1,300        Orange County, California, Special Tax Bonds, Community Facilities District 03-1 of Ladera Ranch,    8/12 at 101.00    N/R    1,353,183 
        Series 2004A, 5.625%, 8/15/34             
 
605        Sacramento City Financing Authority, California, Lease Revenue Refunding Bonds, Series 1993A,    No Opt. Call    AAA    699,997 
        5.400%, 11/01/20 - MBIA Insured             
 
1,000        Santa Clara County Board of Education, California, Certificates of Participation, Series 2002,    4/12 at 101.00    AAA    1,058,850 
        5.000%, 4/01/25 - MBIA Insured             
 
        Transportation - 11.8%             
 
1,150        Foothill/Eastern Transportation Corridor Agency, California, Toll Road Revenue Bonds, Series 1995A,    1/10 at 100.00    BBB-    1,097,986 
        5.000%, 1/01/35             
 
5,000        Los Angeles Harbors Department, California, Revenue Refunding Bonds, Series 2001B, 5.500%, 8/01/17    8/11 at 100.00    AAA    5,470,600 
        (Alternative Minimum Tax) - AMBAC Insured             
 
3,305        Palm Springs Financing Authority, California, Palm Springs Regional Airport Revenue Bonds, Series    7/05 at 100.00    AAA    3,313,196 
        1992, 6.000%, 1/01/12 (Alternative Minimum Tax) - MBIA Insured             
 
1,000        Port of Oakland, California, Revenue Bonds, Series 2002M, 5.250%, 11/01/20 - FGIC Insured    11/12 at 100.00    AAA    1,095,370 
 
        U.S. Guaranteed *** - 6.5%             
 
500        Beverly Hills Unified School District, Los Angeles County, California, General Obligation Bonds,    8/12 at 100.00    AA***    528,830 
        Series 2002A, 5.000%, 8/01/26 (Pre-refunded to 8/01/12)             
 
750        California Educational Facilities Authority, Revenue Bonds, Pepperdine University, Series 2002A,    8/09 at 100.00    A1***    790,635 
        5.500%, 8/01/32 (Pre-refunded to 8/01/09)             
 
2,500        California Health Facilities Financing Authority, Insured Hospital Revenue Bonds, Scripps Memorial    10/05 at 100.00    AAA    2,523,175 
        Hospital, Series 1992A, 6.400%, 10/01/12 (Pre-refunded to 10/01/05) - MBIA Insured             
 
2,000        North Orange County Community College District, California, General Obligation Bonds, Series 2002A,    8/12 at 101.00    AAA    2,232,040 
        5.000%, 8/01/22 (Pre-refunded to 8/01/12) - MBIA Insured             
 
        Utilities - 9.2%             
 
        California Department of Water Resources, Power Supply Revenue Bonds, Series 2002A:             
2,000        5.750%, 5/01/17    5/12 at 101.00    A2    2,255,280 
2,000        5.125%, 5/01/19    5/12 at 101.00    A2    2,155,400 
 
200        Los Angeles Department of Water and Power, California, Power System Revenue Bonds, Series 2003A-2,    7/13 at 100.00    AAA    218,302 
        5.000%, 7/01/21 - MBIA Insured             
 
2,550        M-S-R Public Power Agency, California, Revenue Bonds, San Juan Project, Series 1991E, 6.000%,    7/05 at 100.00    AAA    2,592,840 
        7/01/22 - MBIA Insured             
 
1,225        Turlock Irrigation District, California, Revenue Refunding Bonds, Series 1992A, 6.250%, 1/01/12 -    No Opt. Call    AAA    1,389,395 
        MBIA Insured             
 
        Water and Sewer - 7.7%             
 
2,160        California Statewide Community Development Authority, Water and Wastewater Revenue Bonds, Pooled    10/11 at 101.00    AAA    2,345,198 
        Financing Program, Series 2001B, 5.125%, 10/01/22 - FSA Insured             
 
2,800        Los Angeles, California, Wastewater System Revenue Bonds, Series 1998A, 5.000%, 6/01/23 - FGIC    6/08 at 101.00    AAA    2,949,604 
        Insured             
 
825        South Feather Water and Power Agency, California, Water Revenue Certificates of Participation,    4/13 at 100.00    BBB    836,937 
        Solar Photovoltaic Project, Series 2003, 5.375%, 4/01/24             
 
1,000        Woodbridge Irrigation District, California, Certificates of Participation, Water Systems Project,    7/13 at 100.00    BBB+    1,061,720 
        Series 2003, 5.625%, 7/01/43             
 
$ 91,135        Total Long-Term Investments (cost $85,973,058) - 98.8%            92,018,192 
 
        Other Assets Less Liabilities - 1.2%            1,145,351 
 
        Net Assets - 100%            $93,163,543 
 
 
 
    *    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.             
    **    Ratings: Using the higher of Standard & Poor's or Moody's rating.             
    ***    Securities are backed by an escrow or trust containing sufficient U.S. Government or U.S. Government agency             
        securities which ensures the timely payment of principal and interest. Such securities are normally considered             
        to be equivalent to AAA rated securities.             
    N/R    Investment is not rated.             
 
        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 income on taxable market             
        discount securities and timing differences in recognizing certain gains and losses on investment transactions.             
 
        At June 30, 2005, the cost of investments was $85,972,277.             
 
        Gross unrealized appreciation and gross unrealized depreciation of investments at June 30, 2005, were as             
        follows:             
 
        Gross unrealized:             
           Appreciation            $6,048,887 
           Depreciation            (2,972) 
 
        Net unrealized appreciation of investments            $6,045,915 

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: 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 California Select Tax-Free Income Portfolio        

By (Signature and Title)*          /s/ Jessica R. Droeger--Vice President and Secretary        

Date         08/26/05        

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--Chief Administrative Officer (principal executive officer)        

Date         08/26/05        

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

Date         08/26/05        

* Print the name and title of each signing officer under his or her signature.