Evaluation methods lack direction to improve efforts of teachers because the methods operate on vague impressions. Congruence analysis techniques offer promise for diagnostic determination of strengths and weaknesses in teaching practices over a variety of specified criteria. The analysis circumvents some of the problems of linking objective data to supervisory interventions. As demonstrated by the writer, congruence analysis is based on: (1) multiple data sources to add credibility to findings, (2) collaborative involvement of the teacher in all aspects of the process, (3) congruence analysis procedures following logical rules, and (4) diagnoses that relate to specific alternative courses of action for improving practices. A diagnostic methodology includes events described in detail, data analyzed as related to specific criteria identified, and action alternatives specified. Three data sources include the teacher as a self-reporting "introspector," a supervisor as a systematic "observer-recorder," and a set of students as knowledgeable "interactors.""Congruence analysis illustrations" are presented which diagnose congruent data from two or more sources as either "need for improvement" or "accomplishment." Sample instrumentation for congruence analysis is appended. (CJH)