This document summarizes evidence of the effectiveness of protocol materials in the improvement of teaching. A secondary objective is to place this evaluation in the context of a brief review of protocol materials as an educational innovation, including also its genesis, purpose, problems, and recommendations for the future. The author then reviews the evidence at his disposal, dividing his findings into three sections: a) evidence of changed teacher behavior; b) evidence of concept acquisition; and c) evidence of reaction to the materials. A summary of the findings indicates that: a) no attempt has been made as yet to discover the influence, if any, on the behavior of pupils (probably because most studies are funded for only one year); b) one study reveals the effect of protocols on favorable change of teaching behavior; c) positive results have been obtained on the acquisition of concepts by preservice and in-service teachers; and d) there is evidence of reaction of both trainees and their teachers to the technical quality and relevance of protocol materials. Included are four recommendations pertaining to future evaluations of protocol materials and listings of protocol materials cited in the study and materials reviewed but not applicable to the study. (JA)