The College of American Pathologists (CAP) is a member-based physician organization founded in 1946 comprising approximately 18,000 board-certified pathologists. It serves patients, pathologists, and the public by fostering and advocating excellence in the practice of pathology and laboratory medicine worldwide. The CAP's Laboratory Improvement Programs, initiated 65 years ago, currently has customers in more than 100 countries, accrediting 7,700 laboratories and providing proficiency testing to 20,000 laboratories worldwide. The CAP is the world's largest association composed exclusively of board-certified pathologists and is widely considered the leader in laboratory quality assurance. The organization is an advocate for high-quality and cost-effective medical care.