The Cooperative of American Physicians, Inc. was established in 1975 by a group of California physicians to manage the escalating cost of medical professional liability coverage. Two years later, CAP formed the Mutual Protection Trust, which today provides protection to more than 12,000 of California's finest physicians, and which has earned an A+ (Superior) rating from A.M. Best since 2006.

In 2013, CAP created the CAPAssurance Risk Purchasing Group, allowing hospitals, facilities, and large physician groups access to top-rated liability and risk management services. Based in Los Angeles, CAP also has offices in San Diego, Orange County, Sacramento, and Palo Alto.