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)

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:            8/31          

Date of reporting period:         5/31/07         

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, 2007             
Principal        Optional Call         
Amount (000)    Description (1)    Provisions (2)    Ratings (3)    Value 
    Consumer Staples – 5.3% (3.5% of Total Investments)             
$          6,070    Golden State Tobacco Securitization Corporation, California, Enhanced Tobacco Settlement    6/22 at 100.00    BBB   $   4,599,057 
     Asset-Backed Bonds, Series 2007A-2, 0.000%, 6/01/37             
    Health Care – 11.2% (7.4% of Total Investments)             
1,800    California Infrastructure Economic Development Bank, Revenue Bonds, Kaiser Hospital Assistance    8/11 at 102.00    A+    1,894,734 
     LLC, Series 2001A, 5.550%, 8/01/31             
2,000    California Statewide Community Development Authority, Hospital Revenue Bonds, Monterey    6/13 at 100.00    AAA    2,123,420 
     Peninsula Hospital, Series 2003B, 5.250%, 6/01/23 – FSA Insured             
4,060    California Statewide Community Development Authority, Revenue Bonds, Sherman Oaks Health    No Opt. Call    AAA    4,373,554 
     System, Series 1998A, 5.000%, 8/01/22 – AMBAC Insured             
1,260    Rancho Mirage Joint Powers Financing Authority, California, Revenue Bonds, Eisenhower Medical    7/14 at 100.00    A3    1,370,011 
     Center, Series 2004, 5.875%, 7/01/26             
9,120    Total Health Care            9,761,719 
    Housing/Multifamily – 1.3% (0.9% of Total Investments)             
1,165    Poway, California, Housing Revenue Bonds, Revenue Bonds, Poinsettia Mobile Home Park, Series    5/13 at 102.00    A+    1,183,990 
     2003, 5.000%, 5/01/23             
    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    1,036,000 
     Bonds, Odd Fellows Home of California, Series 2003A, 5.200%, 11/15/22             
2,000    California Health Facilities Financing Authority, Cal-Mortgage Insured Revenue Bonds, Northern    1/13 at 100.00    A+    2,081,760 
     California 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    11/13 at 100.00    A    1,878,271 
     Aging, Series 2003, 5.000%, 11/15/18             
4,815    Total Long-Term Care            4,996,031 
    Tax Obligation/General – 29.4% (19.3% of Total Investments)             
2,000    Butte-Glenn Community College District, Butte and Glenn Counties, California, General    8/12 at 101.00    Aaa    2,082,720 
     Obligation Bonds, Series 2002A, 5.000%, 8/01/26 – MBIA Insured             
    California State, General Obligation Bonds, Series 2002:             
2,460     5.000%, 4/01/27 – AMBAC Insured    4/12 at 100.00    AAA    2,547,305 
55     5.250%, 4/01/30 – XLCA Insured    4/12 at 100.00    AAA    57,696 
1,000    California State, General Obligation Bonds, Series 2007, 4.250%, 12/01/35 – AMBAC Insured    12/16 at 100.00    AAA    931,070 
450    Fremont Unified School District, Alameda County, California, General Obligation Bonds, Series    8/12 at 101.00    AAA    470,102 
     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    4,686,120 
2,030     5.000%, 8/01/27 – FSA Insured    8/13 at 100.00    AAA    2,113,961 
1,540    Los Angeles Unified School District, California, General Obligation Bonds, Series 2006B,    7/16 at 100.00    AAA    1,588,679 
     4.750%, 7/01/25 – FGIC Insured (UB)             
2,000    Los Angeles, California, General Obligation Bonds, Series 2002A, 5.000%, 9/01/22 – MBIA Insured    9/12 at 100.00    AAA    2,083,160 
1,000    Murrieta Valley Unified School District, Riverside County, California, General Obligation    9/13 at 100.00    AAA    1,041,840 
     Bonds, Series 2003A, 5.000%, 9/01/26 – FGIC Insured             
140    Roseville Joint Union High School District, Placer County, California, General Obligation    8/15 at 100.00    AAA    147,223 
     Bonds, Series 2006B, 5.000%, 8/01/27 – FGIC Insured             
3,000    San Diego Unified School District, California, General Obligation Bonds, Election of 1998,    7/10 at 100.00    AAA    3,111,421 
     Series 2000B, 5.125%, 7/01/22 – MBIA Insured             
152    San Diego Unified School District, San Diego County, California, General Obligation Bonds,    7/16 at 101.00    AAA    151,680 
     Series 2006F-1, 4.500%, 7/01/29 – FSA Insured (UB)             
635    San Diego Unified School District, San Diego County, California, General Obligation Bonds,    7/16 at 101.00    AAA    633,660 
     Series 2006G-1, 4.500%, 7/01/29 – FSA Insured (UB)             
3,855    San Rafael City High School District, Marin County, California, General Obligation Bonds,    8/12 at 100.00    AAA    4,000,295 
     Series 2003A, 5.000%, 8/01/28 – FSA Insured             
24,817    Total Tax Obligation/General            25,646,932 
    Tax Obligation/Limited – 41.9% (27.6% of Total Investments)             
550    Baldwin Park Public Financing Authority, California, Sales Tax and Tax Allocation Bonds,    8/13 at 102.00    BBB    577,434 
     Puente Merced Redevelopment Project, Series 2003, 5.250%, 8/01/21             
1,165    Burbank Public Financing Authority, California, Revenue Refunding Bonds, Golden State    12/13 at 100.00    AAA    1,242,135 
     Redevelopment Project, Series 2003A, 5.250%, 12/01/22 – AMBAC Insured             
2,000    California State Public Works Board, Lease Revenue Bonds, Department of Corrections, Series    12/13 at 100.00    A    2,177,020 
     2003C, 5.500%, 6/01/16             
4,000    California State Public Works Board, Lease Revenue Bonds, Department of General Services,    12/12 at 100.00    AAA    4,149,720 
     Capital East End Project, Series 2002A, 5.000%, 12/01/27 – AMBAC Insured             
170    Capistrano Unified School District, Orange County, California, Special Tax Bonds, Community    9/15 at 100.00    AAA    178,843 
     Facilities District, Series 2005, 5.000%, 9/01/24 – FGIC Insured             
525    Chino Redevelopment Agency, California, Merged Chino Redevelopment Project Area Tax Allocation    9/16 at 101.00    AAA    552,279 
     Bonds, Series 2006, 5.000%, 9/01/38 – AMBAC Insured (UB)             
1,000    Coachella Valley Unified School District, Riverside County, California, Certificates of    9/16 at 100.00    Aaa    1,043,970 
     Participation, Series 2007, 5.000%, 9/01/36 – AMBAC Insured             
1,610    Folsom Public Financing Authority, California, Special Tax Revenue Bonds, Series 2004A,    9/12 at 102.00    AAA    1,685,074 
     5.000%, 9/01/21 – AMBAC Insured             
5,540    Irvine Public Facilities and Infrastructure Authority, California, Assessment Revenue Bonds,    9/13 at 100.00    AAA    5,718,720 
     Series 2003C, 5.000%, 9/02/21 – AMBAC Insured             
315    Los Angeles Community Redevelopment Agency, California, Lease Revenue Bonds, Manchester Social    9/15 at 100.00    Aaa    327,383 
     Services Project, Series 2005, 5.000%, 9/01/37 – AMBAC Insured             
1,770    Los Angeles Unified School District, California, Certificates of Participation, Administration    10/12 at 100.00    AAA    1,836,924 
     Building Project II, Series 2002C, 5.000%, 10/01/27 – AMBAC Insured             
2,000    Los Angeles, California, Certificates of Participation, Municipal Improvement Corporation,    6/13 at 100.00    AAA    2,068,540 
     Series 2003AW, 5.000%, 6/01/33 – AMBAC Insured             
1,500    Los Osos, California, Improvement Bonds, Community Services Wastewater Assessment District 1,    9/10 at 103.00    AAA    1,549,440 
     Series 2002, 5.000%, 9/02/33 – MBIA Insured             
1,500    Petaluma Community Development Commission, California, Tax Allocation Bonds, Merged Project    5/17 at 100.00    AAA    1,465,395 
     Area, Series 2007, 4.500%, 5/01/39 – AMBAC Insured             
1,000    Puerto Rico Highway and Transportation Authority, Highway Revenue Bonds, Series 2007N, 5.250%,    No Opt. Call    AAA    1,137,390 
     7/01/32 – MBIA Insured             
150    Rialto Redevelopment Agency, California, Tax Allocation Bonds, Merged Project Area, Series    9/15 at 100.00    AAA    155,792 
     2005A, 5.000%, 9/01/35 – XLCA Insured             
190    Roseville, California, Certificates of Participation, Public Facilities, Series 2003A, 5.000%,    8/13 at 100.00    AAA    197,283 
     8/01/25 – AMBAC Insured             
    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    3,100,590 
3,300     5.000%, 2/01/32 – AMBAC Insured    2/12 at 100.00    AAA    3,391,476 
1,200    San Diego Redevelopment Agency, California, Subordinate Lien Tax Increment and Parking Revenue    9/09 at 101.00    Baa2    1,233,204 
     Bonds, Centre City Project, Series 2003B, 5.250%, 9/01/26             
2,770    San Jose Financing Authority, California, Lease Revenue Refunding Bonds, Civic Center Project,    6/12 at 100.00    AAA    2,851,521 
     Series 2002B, 5.000%, 6/01/32 – AMBAC Insured             
35,255    Total Tax Obligation/Limited            36,640,133 
    Transportation – 10.4% (6.8% of Total Investments)             
5,480    Bay Area Governments Association, California, BART SFO Extension, Airport Premium Fare Revenue    8/12 at 100.00    AAA    5,681,390 
     Bonds, Series 2002A, 5.000%, 8/01/26 – AMBAC Insured             
2,000    Foothill/Eastern Transportation Corridor Agency, California, Toll Road Revenue Bonds, Series    1/10 at 100.00    BBB–    2,032,500 
     1995A, 5.000%, 1/01/35             
1,300    San Francisco Airports Commission, California, Revenue Bonds, San Francisco International    5/10 at 101.00    AAA    1,346,631 
     Airport, Second Series 2000, Issue 26B, 5.000%, 5/01/25 – FGIC Insured             
8,780    Total Transportation            9,060,521 
    U.S. Guaranteed – 28.0% (18.5% of Total Investments) (4)             
1,000    Berryessa Union School District, Santa Clara County, California, General Obligation Bonds,    8/12 at 100.00    AAA    1,056,960 
     Series 2003C, 5.000%, 8/01/21 (Pre-refunded 8/01/12) – FSA Insured             
860    Burbank Public Financing Authority, California, Revenue Refunding Bonds, Golden State    12/13 at 100.00    Aaa    930,967 
     Redevelopment Project, Series 2003A, 5.250%, 12/01/22 (Pre-refunded 12/01/13) – AMBAC Insured             
1,500    California Health Facilities Financing Authority, Revenue Bonds, UCSF – Stanford Healthcare,    11/08 at 101.00    AAA    1,544,700 
     Series 1998A, 5.000%, 11/15/31 (Pre-refunded 11/15/08) – FSA Insured             
    California State, General Obligation Bonds, Series 2002:             
1,290     5.000%, 4/01/27 (Pre-refunded 4/01/12) – AMBAC Insured    4/12 at 100.00    Aaa    1,359,157 
2,945     5.250%, 4/01/30 (Pre-refunded 4/01/12) – XLCA Insured    4/12 at 100.00    Aaa    3,135,129 
    California, General Obligation Bonds, Series 2004:             
1,000     5.125%, 2/01/27 (Pre-refunded 2/01/14)    2/14 at 100.00    A+ (4)    1,073,980 
500     5.250%, 4/01/34 (Pre-refunded 4/01/14)    4/14 at 100.00    A1 (4)    541,525 
1,625    Golden State Tobacco Securitization Corporation, California, Tobacco Settlement Asset-Backed    6/13 at 100.00    AAA    1,964,251 
     Revenue Bonds, Series 2003A-2, 7.900%, 6/01/42 (Pre-refunded 6/01/13)             
8,500    Los Angeles Unified School District, California, General Obligation Bonds, Series 2003A,    7/13 at 100.00    AAA    9,046,717 
     5.000%, 7/01/22 (Pre-refunded 7/01/13) – FSA Insured             
1,220    San Jose Redevelopment Agency, California, Tax Allocation Bonds, Merged Area Redevelopment    8/10 at 101.00    AAA    1,277,230 
     Project, Series 2002, 5.000%, 8/01/32 (Pre-refunded 8/01/10) – MBIA Insured             
2,390    Solano County, California, Certificates of Participation, Series 2002, 5.250%, 11/01/24    11/12 at 100.00    AAA    2,556,320 
     (Pre-refunded 11/01/12) – MBIA Insured             
22,830    Total U.S. Guaranteed            24,486,936 
    Utilities – 5.6% (3.7% of Total Investments)             
1,000    Anaheim Public Finance Authority, California, Second Lien Electric Distribution Revenue Bonds,    10/14 at 100.00    AAA    1,070,510 
     Series 2004, 5.250%, 10/01/21 – MBIA Insured             
3,055    Los Angeles Department of Water and Power, California, Power System Revenue Bonds, Series    7/11 at 100.00    AAA    3,192,750 
     2001A-1, 5.250%, 7/01/22 – FSA Insured             
275    Los Angeles Department of Water and Power, California, Power System Revenue Bonds, Series    7/13 at 100.00    AAA    288,574 
     2003A-2, 5.000%, 7/01/21 – MBIA Insured             
310    Merced Irrigation District, California, Electric System Revenue Bonds, Series 2005, 5.125%,    9/15 at 100.00    AAA    325,934 
     9/01/31 – XLCA Insured             
4,640    Total Utilities            4,877,768 
    Water and Sewer – 12.9% (8.5% of Total Investments)             
215    Healdsburg Public Financing Authority, California, Wastewater Revenue Bonds, Series 2006,    4/16 at 100.00    AAA    224,746 
     5.000%, 4/01/36 – MBIA Insured             
1,055    Manteca Financing Authority, California, Sewerage Revenue Bonds, Series 2003B, 5.000%,    12/13 at 100.00    Aaa    1,057,205 
     12/01/33 – MBIA Insured             
170    Marina Coast Water District, California, Enterprise Certificate of Participation, Series 2006,    6/16 at 100.00    AAA    178,092 
     5.000%, 6/01/31 – MBIA Insured             
370    Sacramento County Sanitation District Financing Authority, California, Revenue Bonds, Series    6/16 at 100.00    AAA    389,022 
     2006, 5.000%, 12/01/36 – FGIC 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    3,123,000 
2,500     5.000%, 8/01/23 – MBIA Insured    8/12 at 100.00    AAA    2,602,500 
1,180    South Feather Water and Power Agency, California, Water Revenue Certificates of Participation,    4/13 at 100.00    BBB    1,233,607 
     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    1,651,424 
     5.000%, 10/01/26 – AMBAC Insured             
750    Westlands Water District, California, Revenue Certificates of Participation, Series 2007A,    9/16 at 100.00    AAA    781,238 
     5.000%, 9/01/37 – MBIA Insured             
10,840    Total Water and Sewer            11,240,834 
$      128,332    Total Investments (cost $127,501,896) – 151.7%            132,493,921 
    Floating Rate Obligations – (2.2)%            (1,902,000) 
    Other Assets Less Liabilities – 2.0%            1,766,146 
    Preferred Shares, at Liquidation Value – (51.5)%            (45,000,000) 
    Net Assets Applicable to Common Shares – 100%           $   87,358,067 

Forward Swaps outstanding at May 31, 2007:                         
        Fund            Fixed Rate            Unrealized 
    Notional    Pay/Receive    Floating Rate    Fixed Rate    Payment    Effective    Termination    Appreciation 
Counterparty    Amount    Floating Rate    Index    (Annualized)    Frequency    Date (5)    Date    (Depreciation) 
Goldman Sachs    $2,000,000    Pay    3-Month USD-LIBOR    5.215%    Semi-Annually    3/12/08    3/12/30    $(97,553) 
USD-LIBOR (United States Dollar-London Inter-Bank Offered Rate)                     

    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 which ensures 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) 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. 
    The Fund may invest in “zero coupon” securities. A zero coupon security does not pay a regular 
    interest coupon to its holders during the life of the security. Tax-exempt income to the holder of 
    the security comes from accretion of the difference between the original purchase price of the 
    security at issuance and the par value of the security at maturity and is effectively paid at 
    maturity. Such securities are included in the portfolio with a 0.00% coupon rate in their 
    description. The market prices of zero coupon securities generally are more volatile than the 
    market prices of securities that pay interest periodically. 
(1)    All percentages shown in the Portfolio of Investments are based on net assets applicable to 
    Common shares unless otherwise noted. 
(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 or Moody’s rating. Ratings below BBB by 
    Standard & Poor’s Group or Baa by Moody’s Investor Service, Inc. are considered to be below 
    investment grade. 
(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)    Effective date represents the date on which both the Fund and counterparty commence interest 
    payment accruals on each forward swap contract. 
(UB)    Underlying bond of an inverse floating rate trust reflected as a financing transaction pursuant 
    to the provisions of SFAS No. 140. 

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 paydown gains and losses, 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.

At May 31, 2007, the cost of investments was $126,075,282.

Gross unrealized appreciation and gross unrealized depreciation of investments at May 31, 2007, were as follows:

Gross unrealized:     
  Appreciation    $5,118,524 
  Depreciation    (601,915) 
Net unrealized appreciation (depreciation) of investments    $4,516,609 

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/ Kevin J. McCarthy                    
                                                    Kevin J. McCarthy
                                                    Vice President and Secretary

Date         July 27, 2007        

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         July 27, 2007        

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

Date        July 27, 2007        

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