This survey project of 129 randomly selected school systems in Ontario, Canada, investigates: (1) dominant patterns among secondary principals' practices and their effectiveness in the improvement of school processes and outcomes; (2) differences in practices between elementary and secondary school principals; (3) factors determining secondary principals' policy implementation; and (4) needs for preservice and inservice education and selection and appraisal. Data summaries appear throughout the report. Section 1 presents the project overview. Section 2 addresses the first objective, to investigate effectiveness. Following 37 interviews, principals were rated according to a profile based on four levels of effectiveness, which incorporated categories relevant to school improvement. The second and third objectives (differences in practices and factors determining policy implementation) are reported in section 3. Elementary and secondary principals were interviewed, and profiles were compared. Advantages among secondary principals, who work in large schools, include delegation of responsibilities to more staff; smaller school elementary principals have better staff communication. Section 4 provides tables of influential factors perceived by principals; agreement with staff and administrators ranks highest in policy implementation. Sections 5 and 6 analyze preservice and inservice education and selection and appraisal (the fourth objective). Section 6 establishes topics for inservice. Recommendations include investigation of school systems' diverse motivations toward exemplary practices and dissemination of knowledge about administrative effectiveness. Sections conclude with references; interviews are appended. (CJH)