A school is a complex organism with many parts. It is necessary to understand the interrelations of these parts to improve schools. In working to improve education for at-risk students, school context must be considered as a factor. The Southwest Educational Development laboratory studied the factors that influence school leaders successfully to implement changes to help students, particularly at-risk students. This cultural approach to school improvement suggests that teachers and students are strongly influenced by the culture of the school, its norms, and conventions. The first section of this report is an introduction. The importance of context in school improvement is the topic of the second section. The third section on the ecology of the school includes these topics: resources; physical arrangements; demographic shifts; working conditions; and local, state, and federal policies. The fourth section on school culture includes information on attitudes and beliefs, attitudes toward change, cultural norms, cultural norms that facilitate school improvement, and relationships. The fifth section on leadership and context covers ecology and culture. Implications for leaders of school improvement and questions for further research are the topics of the final two sections. (Contains 109 references.) (JPT)