This paper synthesizes data from two studies of educational change to describe how school contextual factors influenced teacher involvement and how principals reduced those influences. The first study, involving 14 schools representing a mixture of levels and types of areas served, began in 1979 and spanned 3 school years; the second study, which began in 1981 and is ongoing, involved 12 urban schools representing a mixture of school levels. Following a description of the study's background and methods of inquiry, which included unstructured interviewing, observation, program staff debriefing, and document review yielding approximately 5,000 pages of field notes, the author summarizes the study's findings and discusses in detail its examination of the influences of three major contextual factors: (1) the availability of time and other resources, (2) local concerns and priorities, and (3) staff perceptions of administrative commitment to change. Having described actions taken by principals in both studies and offered suggestions as to what additional measures might be undertaken, the author concludes that principals can in fact reduce the influence of the contextual factors examined, thereby encouraging teacher participation in the planning and implementation of new educational programs and facilitating progress in bringing about change. (JBM)