The techniques and accompanying problems of collecting data on interventions are explored. As a result of the analyses of two previous studies (Colorado and Kentucky Ethnographic Studies, 1979; and Texas, 1981) a hybrid-method of documenting interventions was developed for use in the Principal-Teacher Interaction Study (PTI). This paper traces the development of the methodology for documenting interventions used in the PTI. Nine elementary school principals (three each from Colorado, Florida and California) served as the primary subjects and informants on intervention in this study. The study sites varied by principal's concerns, year of implementation, and innovation being implemented, as well as by school district. Procedures included: bi-weekly telephone calls, interviews, logging, document collections and field notes by researchers; and multiple perspectives and sources of data. In all three studies, the informants provided data on the interventions in which they themselves, as well as others or events, were the sources of action. The methodology employed for the PTI study is as effective and efficient a self-reporting technique in developing the total picture as are the more expensive ethnographic methodologies. (PN)