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)

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 California Select Tax-Free Income Portfolio (NXC)             
    June 30, 2008             
Principal        Optional Call         
Amount (000)    Description (1)    Provisions (2)    Ratings (3)    Value 
    Consumer Staples – 4.4%             
$            200    California County Tobacco Securitization Agency, Tobacco Settlement Asset-Backed Bonds, Sonoma    6/15 at 100.00    BBB   $   183,446 
     County Tobacco Securitization Corporation, Series 2005, 4.250%, 6/01/21             
1,365    California County Tobacco Securitization Agency, Tobacco Settlement Asset-Backed Revenue    6/12 at 100.00    BBB    1,324,077 
     Bonds, Fresno County Tobacco Funding Corporation, Series 2002, 5.625%, 6/01/23             
4,045    Golden State Tobacco Securitization Corporation, California, Enhanced Tobacco Settlement    6/22 at 100.00    BBB    2,327,898 
     Asset-Backed Bonds, Series 2007A-2, 0.000%, 6/01/37             
5,610    Total Consumer Staples            3,835,421 
    Education and Civic Organizations – 9.5%             
1,000    California Educational Facilities Authority, Revenue Bonds, Stanford University, Series 1999P,    12/09 at 101.00    AAA    1,024,190 
     5.000%, 12/01/23             
45    California Educational Facilities Authority, Revenue Bonds, University of Redlands, Series    10/15 at 100.00    A3    43,313 
     2005A, 5.000%, 10/01/35             
1,000    California Educational Facilities Authority, Revenue Bonds, University of San Diego, Series    10/12 at 100.00    A2    1,031,990 
     2002A, 5.500%, 10/01/32             
    California Educational Facilities Authority, Revenue Bonds, University of the Pacific, Series 2006:             
35     5.000%, 11/01/21    11/15 at 100.00    A2    35,647 
45     5.000%, 11/01/25    11/15 at 100.00    A2    45,327 
3,000    California Infrastructure Economic Development Bank, Revenue Bonds, J. David Gladstone    10/11 at 101.00    A–    3,098,310 
     Institutes, Series 2001, 5.500%, 10/01/19             
2,000    California State Public Works Board, Lease Revenue Bonds, University of California, UCLA    10/12 at 100.00    AAA    2,046,720 
     Replacement Hospital Project, Series 2002A, 5.000%, 10/01/22 – FSA Insured             
1,000    Long Beach Bond Financing Authority, California, Lease Revenue Refunding Bonds, Long Beach    11/11 at 101.00    AA    1,000,690 
     Aquarium of the South Pacific, Series 2001, 5.250%, 11/01/30 – AMBAC Insured             
8,125    Total Education and Civic Organizations            8,326,187 
    Health Care – 11.6%             
110    California Health Facilities Financing Authority, Revenue Bonds, Kaiser Permanante System,    4/16 at 100.00    A+    103,528 
     Series 2006, 5.000%, 4/01/37             
2,550    California Health Facilities Financing Authority, Revenue Bonds, Sutter Health, Series 2007A,    11/16 at 100.00    AA–    2,493,466 
     5.250%, 11/15/46 (UB)             
2,000    California Infrastructure Economic Development Bank, Revenue Bonds, Kaiser Hospital Assistance    8/11 at 102.00    A+    2,021,840 
     LLC, Series 2001A, 5.550%, 8/01/31             
1,500    California Statewide Community Development Authority, Hospital Revenue Bonds, Monterey    6/13 at 100.00    AAA    1,578,135 
     Peninsula Hospital, Series 2003B, 5.250%, 6/01/18 – FSA Insured             
1,500    California Statewide Community Development Authority, Insured Mortgage Hospital Revenue Bonds,    11/09 at 102.00    A+    1,515,600 
     Mission Community Hospital, Series 2001, 5.375%, 11/01/26             
545    California Statewide Community Development Authority, Revenue Bonds, Kaiser Permanente System,    8/16 at 100.00    A+    538,863 
     Series 2001C, 5.250%, 8/01/31             
1,880    California Statewide Community Development Authority, Revenue Bonds, Los Angeles Orthopaedic    12/08 at 100.50    AA    1,893,347 
     Hospital Foundation, Series 2000, 5.500%, 6/01/17 – AMBAC Insured             
10,085    Total Health Care            10,144,779 
    Housing/Multifamily – 0.8%             
750    California Statewide Community Development Authority, Student Housing Revenue Bonds, EAH –    8/12 at 100.00    N/R    700,103 
     Irvine East Campus Apartments, LLC Project, Series 2002A, 5.500%, 8/01/22 – ACA Insured             
    Housing/Single Family – 0.2%             
135    California Housing Finance Agency, Home Mortgage Revenue Bonds, Series 2006H, 5.750%,    2/16 at 100.00    Aa2    136,580 
     8/01/30 – FGIC Insured (Alternative Minimum Tax)             
    Industrials – 1.8%             
1,250    California Pollution Control Financing Authority, Solid Waste Disposal Revenue Bonds, Republic    No Opt. Call    BBB+    1,171,675 
     Services Inc., Series 2002C, 5.250%, 6/01/23 (Mandatory put 12/01/17) (Alternative Minimum Tax)             
500    California Pollution Control Financing Authority, Solid Waste Disposal Revenue Bonds, Waste    1/16 at 102.00    BBB    450,105 
     Management Inc., Series 2002A, 5.000%, 1/01/22 (Alternative Minimum Tax)             
1,750    Total Industrials            1,621,780 
    Long-Term Care – 2.8%             
1,500    ABAG Finance Authority for Non-Profit Corporations, California, Insured Senior Living Revenue    11/12 at 100.00    A+    1,518,030 
     Bonds, Odd Fellows Home of California, Series 2003A, 5.200%, 11/15/22             
1,000    California Statewide Communities Development Authority, Revenue Bonds, Inland Regional Center    12/17 at 100.00    Baa1    969,190 
     Project, Series 2007, 5.250%, 12/01/27             
2,500    Total Long-Term Care            2,487,220 
    Tax Obligation/General – 22.3%             
500    California, General Obligation Bonds, Series 2003, 5.250%, 11/01/19 – RAAI Insured    11/13 at 100.00    A+    519,675 
    California, General Obligation Bonds, Series 2004:             
750     5.000%, 2/01/23    2/14 at 100.00    A+    760,913 
800     5.125%, 4/01/25    4/14 at 100.00    A+    813,280 
1,000    Fremont Unified School District, Alameda County, California, General Obligation Bonds, Series    8/12 at 101.00    Aa3    1,017,240 
     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    AA    3,233,191 
1,750     0.000%, 2/01/17 – MBIA Insured    No Opt. Call    AA    1,178,030 
2,375     0.000%, 8/01/17 – MBIA Insured    No Opt. Call    AA    1,559,544 
2,345     0.000%, 2/01/18 – MBIA Insured    No Opt. Call    AA    1,489,474 
    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    AA    674,843 
1,080     0.000%, 5/01/18 – MBIA Insured    No Opt. Call    AA    677,786 
100    Roseville Joint Union High School District, Placer County, California, General Obligation    8/15 at 100.00    AA–    101,365 
     Bonds, Series 2006B, 5.000%, 8/01/27 – FGIC Insured             
3,220    Sacramento City Unified School District, Sacramento County, California, General Obligation    7/15 at 100.00    Aa3    3,282,853 
     Bonds, Series 2005, 5.000%, 7/01/27 – MBIA Insured             
1,500    San Diego Unified School District, San Diego County, California, General Obligation Bonds,    7/13 at 101.00    AAA    1,626,375 
     Series 2003E, 5.250%, 7/01/24 – FSA Insured             
2,565    Sunnyvale School District, Santa Clara County, California, General Obligation Bonds, Series    9/15 at 100.00    AAA    2,641,104 
     2005A, 5.000%, 9/01/26 – FSA Insured             
23,650    Total Tax Obligation/General            19,575,673 
    Tax Obligation/Limited – 19.3%             
1,000    Bell Community Redevelopment Agency, California, Tax Allocation Bonds, Bell Project Area,    10/13 at 100.00    A    1,004,640 
     Series 2003, 5.625%, 10/01/33 – RAAI Insured             
3,500    California State Public Works Board, Lease Revenue Bonds, Department of Corrections,    No Opt. Call    AA    4,024,018 
     Calipatria State Prison, Series 1991A, 6.500%, 9/01/17 – MBIA Insured             
1,000    California State Public Works Board, Lease Revenue Bonds, Department of Mental Health,    6/14 at 100.00    A    1,047,720 
     Coalinga State Hospital, Series 2004A, 5.500%, 6/01/23             
660    California, Economic Recovery Revenue Bonds, Series 2004A, 5.000%, 7/01/15    7/14 at 100.00    AA+    708,378 
120    Capistrano Unified School District, Orange County, California, Special Tax Bonds, Community    9/15 at 100.00    N/R    117,904 
     Facilities District, Series 2005, 5.000%, 9/01/24 – FGIC Insured             
360    Chino Redevelopment Agency, California, Merged Chino Redevelopment Project Area Tax Allocation    9/16 at 101.00    AA    345,370 
     Bonds, Series 2006, 5.000%, 9/01/38 – AMBAC Insured             
1,000    Fontana Public Financing Authority, California, Tax Allocation Revenue Bonds, North Fontana    10/15 at 100.00    AA    984,730 
     Redevelopment Project, Series 2005A, 5.000%, 10/01/32 – AMBAC Insured             
1,050    Golden State Tobacco Securitization Corporation, California, Enhanced Asset Backed Settlement    6/15 at 100.00    Aa3    882,861 
     Revenue Bonds, Series 2005A, Residual Series 1500, 11.070%, 6/01/45 – AMBAC Insured (IF)             
    Irvine, California, Unified School District, Community Facilities District Special Tax Bonds,             
    Series 2006A:             
60     5.000%, 9/01/26    9/16 at 100.00    N/R    53,994 
135     5.125%, 9/01/36    9/16 at 100.00    N/R    119,274 
215    Los Angeles Community Redevelopment Agency, California, Lease Revenue Bonds, Manchester Social    9/15 at 100.00    Aa3    208,879 
     Services Project, Series 2005, 5.000%, 9/01/37 – AMBAC Insured             
1,300    Orange County, California, Special Tax Bonds, Community Facilities District 03-1 of Ladera    8/12 at 101.00    N/R    1,273,766 
     Ranch, Series 2004A, 5.625%, 8/15/34             
105    Rialto Redevelopment Agency, California, Tax Allocation Bonds, Merged Project Area, Series    9/15 at 100.00    A–    101,511 
     2005A, 5.000%, 9/01/35 – XLCA Insured             
130    Roseville, California, Certificates of Participation, Public Facilities, Series 2003A, 5.000%,    8/13 at 100.00    AA    130,689 
     8/01/25 – AMBAC Insured             
605    Sacramento City Financing Authority, California, Lease Revenue Refunding Bonds, Series 1993A,    No Opt. Call    AA    648,663 
     5.400%, 11/01/20 – MBIA Insured             
3,000    San Mateo County Transit District, California, Sales Tax Revenue Bonds, Series 2005A, 5.000%,    6/15 at 100.00    AA    3,117,149 
     6/01/21 – MBIA Insured             
225    San Mateo Union High School District, San Mateo County, California, Certificates of    12/17 at 100.00    AA    218,783 
     Participation, Phase 1, Series 2007A, 5.000%, 12/15/30 – AMBAC Insured             
1,000    Santa Clara County Board of Education, California, Certificates of Participation, Series 2002,    4/12 at 101.00    AA    1,015,130 
     5.000%, 4/01/25 – MBIA Insured             
1,000    Travis Unified School District, Solano County, California, Certificates of Participation,    9/16 at 100.00    N/R    965,200 
     Series 2006, 5.000%, 9/01/26 – FGIC Insured             
16,465    Total Tax Obligation/Limited            16,968,659 
    Transportation – 5.7%             
1,150    Foothill/Eastern Transportation Corridor Agency, California, Toll Road Revenue Bonds, Series    1/10 at 100.00    BBB–    949,728 
     1995A, 5.000%, 1/01/35             
3,500    Los Angeles Harbors Department, California, Revenue Refunding Bonds, Series 2001B, 5.500%,    8/11 at 100.00    AA    3,672,969 
     8/01/17 – AMBAC Insured (Alternative Minimum Tax)             
445    San Francisco Airports Commission, California, Revenue Bonds, San Francisco International    5/09 at 101.00    AA    410,508 
     Airport, Second Series 1999, Issue 23A, 5.000%, 5/01/30 – FGIC Insured (Alternative             
     Minimum Tax)             
5,095    Total Transportation            5,033,205 
    U.S. Guaranteed – 14.7% (4)             
400    Beverly Hills Unified School District, Los Angeles County, California, General Obligation    8/12 at 100.00    AA (4)    428,184 
     Bonds, Series 2002A, 5.000%, 8/01/26 (Pre-refunded 8/01/12)             
    California Department of Water Resources, Power Supply Revenue Bonds, Series 2002A:             
1,750     5.750%, 5/01/17 (Pre-refunded 5/01/12)    5/12 at 101.00    Aaa    1,929,848 
2,000     5.125%, 5/01/19 (Pre-refunded 5/01/12)    5/12 at 101.00    Aaa    2,160,700 
2,600    California Educational Facilities Authority, Revenue Bonds, University of the Pacific, Series    11/11 at 100.00    A2 (4)    2,779,842 
     2002, 5.250%, 11/01/21 (Pre-refunded 11/01/11)             
800    California, General Obligation Bonds, Series 2004, 5.125%, 2/01/27 (Pre-refunded 2/01/14)    2/14 at 100.00    AAA    872,200 
1,400    Golden State Tobacco Securitization Corporation, California, Enhanced Tobacco Settlement    6/13 at 100.00    AAA    1,509,284 
     Asset-Backed Bonds, Series 2003B, 5.500%, 6/01/33 (Pre-refunded 6/01/13)             
2,000    North Orange County Community College District, California, General Obligation Bonds, Series    8/12 at 101.00    AA (4)    2,148,960 
     2002A, 5.000%, 8/01/22 (Pre-refunded 8/01/12) – MBIA Insured             
1,000    Port of Oakland, California, Revenue Bonds, Series 2002M, 5.250%, 11/01/20 (Pre-refunded    11/12 at 100.00    A+ (4)    1,079,060 
     11/01/12) – FGIC Insured             
11,950    Total U.S. Guaranteed            12,908,078 
    Utilities – 5.8%             
645    Long Beach Bond Finance Authority, California, Natural Gas Purchase Revenue Bonds, Series    No Opt. Call    A1    591,549 
     2007A, 5.500%, 11/15/37             
200    Los Angeles Department of Water and Power, California, Power System Revenue Bonds, Series    7/13 at 100.00    AA    205,200 
     2003A-2, 5.000%, 7/01/21 – MBIA Insured             
7,600    Merced Irrigation District, California, Certificates of Participation, Water and Hydroelectric    9/16 at 64.56    A    3,003,140 
     System Projects, Series 2008A, 0.000%, 9/01/23             
215    Merced Irrigation District, California, Electric System Revenue Bonds, Series 2005, 5.125%,    9/15 at 100.00    BBB–    205,987 
     9/01/31 – XLCA Insured             
1,010    Turlock Irrigation District, California, Revenue Refunding Bonds, Series 1992A, 6.250%,    No Opt. Call    A1    1,070,176 
     1/01/12 – MBIA Insured             
9,670    Total Utilities            5,076,052 
    Water and Sewer – 2.5%             
150    Healdsburg Public Financing Authority, California, Wastewater Revenue Bonds, Series 2006,    4/16 at 100.00    AA    147,774 
     5.000%, 4/01/36 – MBIA Insured             
250    Sacramento County Sanitation District Financing Authority, California, Revenue Bonds, Series    6/16 at 100.00    AA    251,453 
     2006, 5.000%, 12/01/31 – FGIC Insured             
825    South Feather Water and Power Agency, California, Water Revenue Certificates of Participation,    4/13 at 100.00    BBB    828,358 
     Solar Photovoltaic Project, Series 2003, 5.375%, 4/01/24             
1,000    Woodbridge Irrigation District, California, Certificates of Participation, Water Systems    7/13 at 100.00    BBB+    993,180 
     Project, Series 2003, 5.625%, 7/01/43             
2,225    Total Water and Sewer            2,220,765 
$         98,010    Total Investments (cost $88,331,127) – 101.4%            89,034,502 
    Floating Rate Obligations – (1.9)%            (1,700,000)
    Other Assets Less Liabilities – 0.5%            477,633 
    Net Assets – 100%          $  87,812,135 

(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. 
N/R    Not rated. 
(IF)    Inverse floating rate investment. 
(UB)    Underlying bond of an inverse floating rate trust reflected as a financing transaction pursuant to the 
    provisions of the SFAS No. 140. 

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    $—    $89,034,502    $—    $89,034,502 

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 the treatment of 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 $86,678,746.

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

Gross unrealized:     
  Appreciation    $ 2,617,860 
  Depreciation    (1,962,103)
Net unrealized appreciation (depreciation) of investments    $    655,757 

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 California 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