This report is part of a research series on roles of participants in high school change. Investigators administered interview questions to 380 teachers of 18 selected high schools in 9 sites geographically dispersed across the nation. From taped interviews, 54 were chosen for study of teachers' roles in school change, their reactions to change, and factors that influenced those reactions. The 54 teachers reported a total of 155 changes that had influenced them during the previous two years. Data indicate that high school teachers are more likely to be recipients than initiators of change. As individuals working collaboratively, teachers were responsible for initiating 28.4 percent of changes, whereas 71.6 percent were begun by school administrators or sources outside the school. In their reactions to changes, teachers were more likely to be positive than negative, thereby invalidating the common assumption that teachers are resistant to change. Investigation of influences on teacher reactions to change revealed that source of change was the most significant factor. This suggests that future research should identify the role teachers can and should assume to enhance school improvement efforts. (CJH)