The first internal affairs units were established in the 1940's. During the late 1950's and the 1960's, external review mechanisms were developed either in addition to or as replacements for internal review mechanisms. Since then opinion has remained polarized on the issue of internal versus external review. During the 1980's, the Commission on Accreditation for Law Enforcement Agencies and the International Association for Civilian Oversight of Law Enforcement have been formed, and the Police Executive Research Forum has become increasingly involved in researching the issues. The experiences in different police agencies show that no single best model exists. Instead, factors such as community attitudes, the presence of police misconduct, allegations of police department coverups and the sociopolitical environment of the community must all be considered in developing a complaint review program. Case examples, 70 references, and 5 study questions