The Art of the Metaobject Protocol (AMOP) is a 1991 book by Gregor Kiczales, Jim des Rivieres, and Daniel G. Bobrow on metaobject protocol. It contains an explanation of what a metaobject protocol is, why it is desirable, and the de facto standard for the metaobject protocol supported by many Common Lisp implementations as an extension of the Common Lisp Object System, or CLOS.