A classification of school environments is developed by using information about the ecological, demographic, organizational, and psychosocial climates of 642 junior and senior high schools. Hierarchical clustering techniques are used to provide simple multivariate descriptions of patterns in school environmental characteristics. Two major dimensions are identified--urban disorganization and academic suburbanism. The clustering of schools with similar levels of disruption, but with different profiles of school characteristics, implies that different approaches to increasing orderliness may be in demand. These observations suggest the possibility of developing a diagnostic scheme to specify school interventions to reduce or prevent trouble for particular schools. The results imply that the experiences of students in the school are different indeed in central city and suburban schools: that suburban schools tend to have newer and better facilities, more helpful teachers, and more teaching resources than the central city schools. Differences also emerge concerning administrative and organizational aspects. While it would be difficult to drastically alter the demographic composition of schools or their community contexts, there are aspects of school organization which are potentially more manipulable. Manning ratios can be altered by reorganizing schools into subunits, by resisting the temptation to close schools as enrollments shrink, and by taking imaginative steps to increase the numbers of behavior settings (and therefore the number of roles for students) in schools. Similarly, administrative styles can be altered, either by replacing personnel or teaching new and more positive styles. Extensive tables and diagrams illustrate the clusters discovered in the study, while appendixes describe the measures used and some of the clusters of schools studied. A total of 19 references are included.