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         811-21212         

        Nuveen Insured California Tax-Free Advantage Municipal Fund         
(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:            08/31          

Date of reporting period:          05/31/05         

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 Insured California Tax-Free Advantage Municipal Fund (NKX)                     
                   May 31, 2005                     
 
 
 
 
Principal            Optional Call        Market 
Amount (000)    Description(1)        Provisions*    Ratings**    Value 
 
    Consumer Staples - 2.2% (1.5% of Total Investments)                     
$ 1,625    Golden State Tobacco Securitization Corporation, California, Tobacco Settlement Asset-Backed        6/13 at 100.00    BBB    $ 1,913,259 
    Revenue Bonds, Series 2003A-2, 7.900%, 6/01/42                     
 
    Healthcare - 18.7% (12.5% of Total Investments)                     
2,700    California Health Facilities Financing Authority, Revenue Bonds, Cedars-Sinai Medical Center,        12/09 at 101.00    A3    2,945,457 
    Series 1999A, 6.250%, 12/01/34                     
1,500    California Health Facilities Financing Authority, Revenue Bonds, UCSF - Stanford Healthcare, Series    11/08 at 101.00    AAA    1,576,890 
    1998A, 5.000%, 11/15/31 - FSA Insured                     
1,800    California Infrastructure Economic Development Bank, Revenue Bonds, Kaiser Hospital Assistance LLC,    8/11 at 102.00    A+    1,932,264 
    Series 2001A, 5.550%, 8/01/31                     
6,000    California Statewide Community Development Authority, Revenue Bonds, Sherman Oaks Health System,    No Opt. Call    AAA    6,648,780 
    Series 1998A, 5.000%, 8/01/22 - AMBAC Insured                     
2,000    California Statewide Community Development Authority, Hospital Revenue Bonds, Monterey Peninsula    6/13 at 100.00    AAA    2,164,740 
    Hospital, Series 2003B, 5.250%, 6/01/23 - FSA Insured                     
1,260    Rancho Mirage Joint Powers Financing Authority, California, Revenue Bonds, Eisenhower Medical    7/14 at 100.00    A3    1,381,552 
    Center, Series 2004, 5.875%, 7/01/26                     
 
    Long-Term Care - 5.7% (3.8% of Total Investments)                     
1,000    ABAG Finance Authority for Non-Profit Corporations, California, Insured Senior Living Revenue        11/12 at 100.00    A    1,061,260 
    Bonds, Odd Fellows Home of California, Series 2003A, 5.200%, 11/15/22                     
2,000    California Health Facilities Financing Authority, Insured Revenue Bonds, Northern California        1/13 at 100.00    A    2,115,800 
    Retired Officers Community Corporation - Paradise Valley Estates, Series 2002, 5.250%, 1/01/26                 
1,815    California Statewide Community Development Authority, Revenue Bonds, Jewish Home for the Aging,    11/13 at 100.00    A    1,928,692 
    Series 2003, 5.000%, 11/15/18                     
 
    Tax Obligation/General - 48.5% (32.4% of Total Investments)                     
1,000    Berryessa Union School District, Santa Clara County, California, General Obligation Bonds, Series    8/12 at 100.00    AAA    1,064,290 
    2003C, 5.000%, 8/01/21 - FSA Insured                     
2,000    Butte-Glenn Community College District, Butte and Glenn Counties, California, General Obligation    8/12 at 101.00    Aaa    2,125,880 
    Bonds, Series 2002A, 5.000%, 8/01/26 - MBIA Insured                     
    California, General Obligation Refunding Bonds, Series 2002:                     
1,500    5.000%, 2/01/12        No Opt. Call    A    1,640,715 
3,750    5.000%, 4/01/27 - AMBAC Insured        4/12 at 100.00    AAA    3,934,350 
3,000    5.250%, 4/01/30 - XLCA Insured        4/12 at 100.00    AAA    3,210,090 
500    California, General Obligation Bonds, Series 2004, 5.250%, 4/01/34        4/14 at 100.00    A    535,145 
450    Fremont Unified School District, Alameda County, California, General Obligation Bonds, Series        8/12 at 101.00    AAA    480,870 
    2002A, 5.000%, 8/01/25 - FGIC Insured                     
    Hacienda La Puente Unified School District, Los Angeles County, California, General Obligation                 
    Bonds, Series 2003B:                     
4,500    5.000%, 8/01/26 - FSA Insured        8/13 at 100.00    AAA    4,783,230 
2,030    5.000%, 8/01/27 - FSA Insured        8/13 at 100.00    AAA    2,153,424 
2,000    Los Angeles, California, General Obligation Bonds, Series 2002A, 5.000%, 9/01/22 - MBIA Insured    9/12 at 100.00    AAA    2,129,860 
565    Los Angeles Community College District, Los Angeles County, California, General Obligation Bonds,    8/15 at 100.00    AAA    606,657 
    Series 2005A, 5.000%, 6/01/26 - FSA Insured                     
10,750    Los Angeles Unified School District, California, General Obligation Bonds, Series 2003A, 5.000%,    7/13 at 100.00    AAA    11,614,623 
    7/01/22 - FSA Insured                     
1,000    Murrieta Valley Unified School District, Riverside County, California, General Obligation Bonds,        9/13 at 100.00    AAA    1,063,480 
    Series 2003A, 5.000%, 9/01/26 - FGIC Insured                     
3,000    San Diego Unified School District, California, General Obligation Bonds, Election of 1998, Series    7/10 at 100.00    AAA    3,281,400 
    2000B, 5.125%, 7/01/22 - MBIA Insured                     
    San Jose-Evergreen Community College District, Santa Clara County, California, General Obligation                 
    Bonds, Series 2005A:                     
145    5.000%, 9/01/25 - MBIA Insured        9/15 at 100.00    AAA    156,137 
215    5.000%, 9/01/27 - MBIA Insured        9/15 at 100.00    AAA    230,396 
3,855    San Rafael City High School District, Marin County, California, General Obligation Bonds, Series    8/12 at 100.00    AAA    4,062,245 
    2003A, 5.000%, 8/01/28 - FSA Insured                     
 
    Tax Obligation/Limited - 43.9% (29.4% of Total Investments)                     
550    Baldwin Park Public Financing Authority, California, Sales Tax and Tax Allocation Bonds, Puente    8/13 at 102.00    BBB    580,311 
    Merced Redevelopment Project, Series 2003, 5.250%, 8/01/21                     
2,025    Burbank Public Financing Authority, California, Revenue Refunding Bonds, Golden State Redevelopment    12/13 at 100.00    AAA    2,212,738 
    Project, Series 2003A, 5.250%, 12/01/22 - AMBAC Insured                     
4,000    California State Public Works Board, Lease Revenue Bonds, Department of General Services, Capital    12/12 at 100.00    AAA    4,205,360 
    East End Project, Series 2002A, 5.000%, 12/01/27 - AMBAC Insured                     
2,000    California State Public Works Board, Lease Revenue Bonds, Department of Corrections, Series 2003C,    12/13 at 100.00    A-    2,239,600 
    5.500%, 6/01/16                     
1,610    Folsom Public Financing Authority, California, Special Tax Revenue Bonds, Series 2004A, 5.000%,    9/12 at 102.00    AAA    1,734,002 
    9/01/21 - AMBAC Insured                     
130    Hesperia Community Redevelopment Agency, California, Tax Allocation Bonds, Series 2005A,    5.000%,    9/15 at 100.00    AAA    140,438 
    9/01/20 (WI, settling 6/07/05) - XLCA Insured                     
5,540    Irvine Public Facilities and Infrastructure Authority, California, Assessment Revenue Bonds, Series    9/05 at 103.00    AAA    5,728,748 
    2003C, 5.000%, 9/02/21 - AMBAC Insured                     
2,000    Los Angeles, California, Certificates of Participation, Municipal Improvement Corporation, Series    6/13 at 100.00    AAA    2,098,760 
    2003AW, 5.000%, 6/01/33 - AMBAC Insured                     
1,770    Los Angeles Unified School District, California, Certificates of Participation, Administration        10/12 at 100.00    AAA    1,859,049 
    Building Project II, Series 2002C, 5.000%, 10/01/27 - AMBAC Insured                     
1,500    Los Osos, California, Improvement Bonds, Community Services Wastewater Assessment District 1,    9/10 at 103.00    AAA    1,572,030 
    Series 2002, 5.000%, 9/02/33 - MBIA Insured                     
825    Paramount Redevelopment Agency, California, Tax Allocation Bonds, Redevelopment Project Area 1,    8/13 at 100.00    AAA    887,007 
    Series 2003, 5.000%, 8/01/19 - MBIA Insured                     
1,165    Poway, California, Housing Revenue Bonds, Revenue Bonds, Poinsettia Mobile Home Park, Series 2003,    5/13 at 102.00    BBB+    1,182,708 
    5.000%, 5/01/23                     
    San Buenaventura, California, Certificates of Participation, Golf Course Financing Project, Series                 
    2002D:                     
3,000    5.000%, 2/01/27 - AMBAC Insured        2/12 at 100.00    AAA    3,139,020 
3,300    5.000%, 2/01/32 - AMBAC Insured        2/12 at 100.00    AAA    3,442,758 
1,200    San Diego Redevelopment Agency, California, Subordinate Lien Tax Increment and Parking Revenue    9/09 at 101.00    Baa2    1,242,660 
    Bonds, Centre City Project, Series 2003B, 5.250%, 9/01/26                     
1,220    San Jose Redevelopment Agency, California, Tax Allocation Bonds, Merged Area Redevelopment Project,    8/10 at 101.00    AAA    1,268,641 
    Series 2002, 5.000%, 8/01/32 - MBIA Insured                     
2,770    San Jose Financing Authority, California, Lease Revenue Refunding Bonds, Civic Center Project,    6/12 at 100.00    AAA    2,894,151 
    Series 2002B, 5.000%, 6/01/32 - AMBAC Insured                     
2,390    Solano County, California, Certificates of Participation, Series 2002, 5.250%, 11/01/24 - MBIA        11/12 at 100.00    AAA    2,608,852 
    Insured                     
 
    Transportation - 13.9% (9.3% of Total Investments)                     
5,480    Bay Area Governments Association, California, BART SFO Extension, Airport Premium Fare Revenue    8/12 at 100.00    AAA    5,760,686 
    Bonds, Series 2002A, 5.000%, 8/01/26 - AMBAC Insured                     
2,000    Foothill/Eastern Transportation Corridor Agency, California, Toll Road Revenue Bonds, Series 1995A,    1/10 at 100.00    BBB-    1,892,260 
    5.000%, 1/01/35                     
3,135    San Francisco Airports Commission, California, Revenue Bonds, San Francisco International Airport,    5/08 at 101.00    AAA    3,292,565 
    Second Series Issue 16B, 5.000%, 5/01/24 - FSA Insured                     
1,300    San Francisco Airports Commission, California, Revenue Bonds, San Francisco International Airport,    5/10 at 101.00    AAA    1,374,126 
    Second Series 2000, Issue 26B, 5.000%, 5/01/25 - FGIC Insured                     
 
    Utilities - 5.3% (3.5% of Total Investments)                     
1,000    Anaheim Public Finance Authority, California, Second Lien Electric Distribution Revenue Bonds,    10/14 at 100.00    AAA    1,103,480 
    Series 2004, 5.250%, 10/01/21 - MBIA Insured                     
3,055    Los Angeles Department of Water and Power, California, Power System Revenue Bonds, Series 2001A-1,    7/11 at 100.00    AAA    3,300,378 
    5.250%, 7/01/22 - FSA Insured                     
275    Los Angeles Department of Water and Power, California, Power System Revenue Bonds, Series 2003A-2,    7/13 at 100.00    AAA    298,232 
    5.000%, 7/01/21 - MBIA Insured                     
 
    Water and Sewer - 11.3% (7.6% of Total Investments)                     
1,285    Manteca Financing Authority, California, Sewerage Revenue Bonds, Series 2003B, 5.000%, 12/01/33 -    12/13 at 100.00    Aaa    1,303,928 
    MBIA Insured                     
    San Diego Public Facilities Financing Authority, California, Subordinate Lien Water Revenue Bonds,                 
    Series 2002:                     
3,000    5.000%, 8/01/22 - MBIA Insured        8/12 at 100.00    AAA    3,192,870 
2,500    5.000%, 8/01/23 - MBIA Insured        8/12 at 100.00    AAA    2,660,725 
1,180    South Feather Water and Power Agency, California, Water Revenue Certificates of Participation,    4/13 at 100.00    BBB    1,196,472 
    Solar Photovoltaic Project, Series 2003, 5.375%, 4/01/24                     
1,600    Sunnyvale Financing Authority, California, Water and Wastewater Revenue Bonds, Series 2001,    10/11 at 100.00    AAA    1,678,160 
    5.000%, 10/01/26 - AMBAC Insured                     
 
$ 124,765    Total Long-Term Investments (cost $125,672,696) - 149.5%                    132,832,201 
 
    Other Assets Less Liabilities - 1.2%                    999,477 
 
    Preferred Shares, at Liquidation Value - (50.7)%                    (45,000,000) 
 
    Net Assets Applicable to Common Shares - 100%                    $88,831,678 
 
 
 
    Forward Swaps outstanding at May 31, 2005:                     
                        Unrealized 
        Notional    Effective    Termination    Appreciation 
        Amount     Date(2)        Date    (Depreciation) 
 
    Agreement with Goldman Sachs dated December 6, 2004, to pay                     
    semi-annually the notional amount multiplied by 5.324% (annualized)                     
    and receive quarterly the notional amount multiplied by the                     
    three-month USD-LIBOR (United States Dollar-London                     
    Inter-Bank Offered Rates).    $2,400,000     7/11/05        7/11/25    $(192,004) 
 
    Agreement with JPMorgan dated January 11, 2005, to pay semi-                     
    annually the notional amount multiplied by 5.235% (annualized)                     
    and receive quarterly the notional amount multiplied by the three-month                     
    USD-LIBOR (United States Dollar-London Inter-Bank Offered Rates).    2,300,000     8/17/05        8/17/25    (153,551) 
 
    Agreement with Merrill Lynch dated February 14, 2005, to pay semi-                     
    annually the notional amount multiplied by 4.886% (annualized)                     
    and receive quarterly the notional amount multiplied by the three-month                     
    USD-LIBOR (United States Dollar-London Inter-Bank Offered Rates).    2,700,000     8/24/05        8/24/25    (57,662) 
 
                        $(403,217) 
 
 
 
    At least 80% of the Fund's net assets (including net assets attributable to Preferred shares) are invested in                 
    municipal securities that are either covered by Original Issue Insurance, Secondary Market Insurance or                 
    Portfolio Insurance any of which ensure the timely payment of principal and interest. Up to 20% of the Fund's                 
    net assets (including net assets attributable to Preferred shares) may be invested in municipal securities that                 
    are (i) either backed by an escrow or trust containing sufficient U.S. Government or U.S. Government agency                 
    securities (also ensuring the timely payment of principal and interest), or (ii) municipal bonds that are rated,                 
    at the time of investment, within the four highest grades (Baa or BBB or better by Moody's, S&P or Fitch) or                 
    unrated but judged to be of comparable quality by the Adviser.                     
(1)    All percentages shown in the Portfolio of Investments are based on net assets applicable to Common shares                 
    unles otherwise noted.                     
(2)    Effective date represents the date on which both the Fund and counterparty commence interest payment accruals                 
    on each forward swap contract.                     
*    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.                     
(WI)    Security purchased on a when-issued basis.                     
 
    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 May 31, 2005, the cost of investments was $125,666,216.                     
 
    Gross unrealized appreciation and gross unrealized depreciation of investments at May 31, 2005, were as                 
    follows:                     
 
    Gross unrealized:                     
       Appreciation                    $7,217,554 
       Depreciation                    (51,569) 
 
    Net unrealized appreciation of investments                    $7,165,985 

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 Insured California Tax-Free Advantage Municipal Fund        

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

Date         07/29/05        

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         07/29/05        

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

Date         07/29/05        

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