UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM N-Q

QUARTERLY SCHEDULE OF PORTFOLIO HOLDINGS OF REGISTERED
MANAGEMENT INVESTMENT COMPANY

Investment Company Act file number:           811-21177               

                         BlackRock California Insured Municipal Income Trust                         
(Exact name of registrant as specified in charter)

 

                    100 Bellevue Parkway, Wilmington, DE                                     19809                
(Address of principal executive offices) 
(Zip code) 

Robert S. Kapito, President
BlackRock California Insured Municipal Income Trust
40 East 52nd Street, New York, NY 10022
(Name and address of agent for service)

Registrant's telephone number, including area code:           888-825-2257               

Date of fiscal year end:           August 31, 2006               

Date of reporting period:           May 31, 2006               

Item 1. Schedule of Investments.
The Registrant’s unaudited schedule of investments as of the close of the reporting period pursuant to Rule 30b1-5 under the Investment Company Act of 1940 is as follows:

PORTFOLIO OF INVESTMENTS (unaudited)
MAY 31, 2006

BlackRock California Insured Municipal Income Trust (BCK)

  Principal          
    Amount       Option Call  
Rating1   (000)   Description   Provisions2   Value  
          LONG-TERM INVESTMENTS—156.4%        
        California—156.4%        
AAA   $ 6,500   Benicia Unified Sch. Dist. GO, Ser. B, Zero Coupon, 8/01/23, MBIA   No Opt. Call   $ 2,856,750  
AAA   4,000   California St. GO, 5.00%, 6/01/31, AMBAC   12/14 @ 100   4,111,360  
        Ceres Unified Sch. Dist. GO,        
AAA   3,055           Ser. B, Zero Coupon, 8/01/30, FGIC   08/12 @ 34.887   780,308  
AAA   3,180           Ser. B, Zero Coupon, 8/01/31, FGIC   08/12 @ 32.868   764,758  
AAA   3,300           Ser. B, Zero Coupon, 8/01/32, FGIC   08/12 @ 30.966   747,252  
AAA   3,440           Ser. B, Zero Coupon, 8/01/33, FGIC   08/12 @ 29.174   733,442  
AAA   3,575           Ser. B, Zero Coupon, 8/01/34, FGIC   08/12 @ 27.782   725,403  
AAA   3,275           Ser. B, Zero Coupon, 8/01/35, FGIC   08/12 @ 26.186   626,377  
A   6,500 3 Dept. of Wtr. Res. Pwr. Sply. RB, Ser. A, 5.25%, 5/01/12   N/A   7,082,205  
AAA   2,385   Edl. Facs. Auth. RB, Scripps Coll. Proj., 5.00%, 8/01/31, MBIA   08/11 @ 100   2,432,581  
        Infrastructure & Econ. Dev. RB,        
AAA   4,500 4         Auth. Rand Corp. Proj., Ser. A, 5.25%, 4/01/42, AMBAC   04/12 @ 100   4,659,255  
AAA   2,300 3         Bay Area Toll Brdgs. Proj., Ser. A, 5.00%, 1/01/28, AMBAC   N/A   2,467,555  
A3   2,600   Kaweah Delta Hlth. Care Dist. RB, 6.00%, 8/01/34   08/12 @ 102   2,784,496  
AAA   2,000   Long Beach Unified Sch. Dist. GO, Ser. D, 5.00%, 8/01/31, FSA   08/10 @ 101   2,044,520  
        Los Angeles Dept. of Wtr. & Pwr. Wtr. Wks. RB,        
AAA   5,000           Ser. A, 5.00%, 7/01/43, FGIC   07/12 @ 100   5,094,150  
AAA   5,000           Ser. A, 5.125%, 7/01/41, FGIC   07/11 @ 100   5,106,050  
AAA   5,000   Los Angeles Unified Sch. Dist. GO, Ser. E, 5.125%, 1/01/27, MBIA   07/12 @ 100   5,218,250  
        Los Angeles Wstwtr. Sys. RB,        
AAA   5,000           Ser. A, 5.00%, 6/01/27, MBIA   06/13 @ 100   5,151,800  
AAA   6,025           Ser. A, 5.00%, 6/01/32, FGIC   06/12 @ 100   6,159,357  
AAA   5,000   No. California Pwr. Agcy. Pub. Pwr. RB, Hydroelec. Proj. 1, Ser. A, 5.00%, 7/01/28, MBIA   07/08 @ 101   5,124,300  
AAA   2,500 3 No. Orange Cnty. Cmnty. Coll. Dist. GO, Ser. A, 5.00%, 8/01/12, MBIA   N/A   2,684,425  
AAA   5,000   Pub. Wks. Brd. Dept. of Gen. Svcs. RB, Ser. A, 5.00%, 12/01/27, AMBAC   12/12 @ 100   5,116,700  
AAA   5,000   Riverside Unified Sch. Dist. GO, Ser. A, 5.00%, 2/01/27, FGIC   02/12 @ 101   5,147,900  
AAA   690   San Carlos Sch. Dist. Election 2005 GO, Ser. A, 5.00%, 10/01/30, MBIA   10/16 @ 100   713,005  
AAA   4,000   San Diego Cmnty. Coll. GO, 5.00%, 5/01/30, FSA   05/15 @ 100   4,133,400  
AAA   5,295   San Diego Cnty. Wtr. Auth. COP, Ser. A, 5.00%, 5/01/32, MBIA   05/12 @ 101   5,409,743  
AAA   4,805   San Diego Redev. Agcy. TA, Ctr. City Proj., Ser. A, 5.00%, 9/01/28, MBIA   09/11 @ 101   4,921,858  
AAA   4,000   San Diego Univ. Fndtn. Auxiliary Org. RB, Ser. A, 5.00%, 3/01/37, MBIA   03/12 @ 100   4,059,480  
AAA   20,000   San Joaquin Hills Transp. Corridor Agcy. Toll Rd. RB, Ser. A, Zero Coupon, 1/15/31, MBIA   No Opt. Call   5,875,000  
AAA   6,000   San Jose Fin. Auth. RB, Civic Ctr. Proj., Ser. B, 5.00%, 6/01/37, AMBAC   06/12 @ 100   6,077,340  
AAA   11,125   Santa Rosa Wstwtr. RB, Ser. B, Zero Coupon, 9/01/27, AMBAC   No Opt. Call   3,938,027  
AAA   3,000   Tustin Unified Sch. Dist. ST, Cmnty. Facs. Dist. 97-1 Proj., Ser. A, 5.00%, 9/01/38, FSA   09/12 @ 100   3,039,870  
AAA   3,000   West Valley-Mission Cmnty. Coll. Dist. Election 2004 GO, 4.75%, 8/01/30, FSA   08/16 @ 100   3,004,620  
AAA   4,000   Westlands Wtr. Dist. COP, 5.00%, 9/01/34, MBIA   09/12 @ 101   4,075,080  
        Total Investments—156.4% (cost $118,921,4235)       $122,866,617  
        Other assets in excess of liabilities—2.8%       2,236,202  
        Preferred shares at redemption value, including dividends payable—(59.2)%       (46,502,242)  
        Net Assets Applicable to Common Shareholders—100%    
$ 78,600,577
  

1

BlackRock California Insured Municipal Income Trust (BCK)   

1   Using the higher of Standard & Poor’s, Moody’s Investors Service or Fitch’s rating.  
2   Date (month/year) and price of the earliest optional call or redemption. There may be other call provisions at varying prices at later dates.  
3   This bond is prerefunded. U.S. government securities, held in escrow, are used to pay interest on this security, as well as retire the bond in full at the date indicated, typically at a premium to par.  
4   Security pledged as collateral.  
5   Cost for Federal income tax purposes is $118,921,941. The net unrealized appreciation on a tax basis is $3,944,676, consisting of $3,945,276 gross unrealized appreciation and $600 gross unrealized depreciation.  
 
    The value (market value plus accrued interest) of securities that are covered by insurance, which ensures the payment of principal and interest, represent approximately 91.6% of the Trust’s managed assets. 

  AMBAC — 21.4%    
  FGIC — 21.1%    
  FSA — 9.8%    
  MBIA — 39.3%  

KEY TO ABBREVIATIONS

AMBAC — American Municipal Bond Assurance Corp. MBIA — Municipal Bond Insurance Assoc.
COP — Certificate of Participation RB — Revenue Bond
FGIC — Financial Guaranty Insurance Co. ST — Special Tax
FSA — Financial Security Assurance TA — Tax Allocation
GO — General Obligation  
 

2  

Item 2. Controls and Procedures.
(a) The Registrant's principal executive and principal financial officers have evaluated the Registrant's disclosure controls and procedures within 90 days of this filing and have concluded, as of that date, that the Registrant’s disclosure controls and procedures were reasonably designed to ensure that information required to be disclosed by the Registrant in this Form N-Q was recorded, processed, summarized, and reported within the required time periods and that information to be disclosed by the Registrant in this Form N-Q was accumulated and communicated to the Registrant’s management, including its principal executive and principal financial officers, as appropriate, to allow timely decisions regarding required disclosure.

(b) 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.
Separate certifications of the Registrant’s Principal Executive and Financial Officers pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 are attached as EX-99.CERT.

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)                BlackRock California Insured Municipal Income Trust               

By:       /s/   Henry Gabbay                
Name: Henry Gabbay
Title: Treasurer and Principal Financial Officer
Date: July 26, 2006

     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:       /s/   Robert S. Kapito                
Name: Robert S. Kapito
Title: President and Principal Executive Officer
Date: July 26, 2006

By:       /s/   Henry Gabbay                
Name: Henry Gabbay
Title: Treasurer and Principal Financial Officer
Date: July 26, 2006