To assess the effects of principal turnover on school organizational structures and effectiveness at elementary and secondary levels, the operations of schools that changed principals were compared to those that retained principals. Studies of organizational dynamics have identified important structural variables that can be applied to school settings, including such variables as organizational linkages that affect instruction (particularly those among school specialists, principals, and teachers). These studies have also revealed effectiveness indicators, including staff perception of effectiveness and job satisfaction and student attitudes toward school. A project conducted at 89 schools in a midwestern state--37 schools with new and 52 with continuing principals--sampled the opinions of teachers on organizational and instructional effectiveness by means of variously derived indexes that measured such institutional variables as intensity of work system interdependence, communication, school discipline, isolation, perceived organizational effectiveness, and indicators of job satisfaction; in addition, students responded to nine items describing their attitudes and the school climate. After the scored responses were averaged, no evidence was found either that principal succession has a significant effect on structural linkages or that succession increases or decreases organizational effectiveness. Further research should examine factors maintaining continuity in structures, possible time-lag effects of turnovers, and the pre- and postarrival phases of principal succession. (JW)