Exhibit 23

[DELOITTE LOGO]

CONSENT OF INDEPENDENT REGISTERED ACCOUNTING FIRM

We consent to the incorporation by reference in the Registration Statement No. 333-68855 of PMA Capital Corporation on Form S-8 of our report dated June 23, 2005, appearing in this Annual Report on Form 11-K of the PMA Capital Corporation 401(k) Plan for the year ended December 31, 2004.

/s/ Deloitte & Touche LLP

Philadelphia, PA

June 23, 2005