“Firms (and individuals) enrolled in the AICPA Peer Review Program are required to have a peer review, once every three years, of their accounting and auditing practice… The peer review is conducted by an independent evaluator, known as a peer reviewer. The AICPA oversees the program, and the review is administered by an entity approved by the AICPA to perform that role.”

-More on Peer Reviews at AICPA.org