A national study was conducted to determine the means by which school districts choose principals. The main goals of the study were to describe and characterize both common practices in principal selection and promising alternatives for improvement of common practice. Accordingly, the study was designed in two phases. In phase 1, field research teams closely investigated selection practices in 10 randomly sampled, geographically dispersed school districts with enrollments of 10,000 or more students. In phase 2, three alternative selection models (based on the needs revealed in phase 1) were chosen for study: (1) assessment centers, (2) district-operated internships, and (3) "exemplary" conventional practices. Five school districts were selected to represent these alternatives. In addition to the research report, the study produced a practical manual or sourcebook for use by school boards and administrators to improve methods of selection. Major research findings are described, followed by descriptions of each alternative model, in this executive summary of the project. (TE)