This research project examined student performance in middle schools with a grade configuration of six through eight. Schools were categorized into two groups: high-performing middle schools--middle schools making adequate yearly progress for two consecutive school years, and low-performing middle schools--middle schools not making adequate yearly progress for two consecutive school years. Participants included 283 middle school teachers, 171 from high-performing middle schools, and 112 from low-performing middle schools. Questionnaires were used to gather information about middle school practices, school climate, and school health. Data suggested that low-performing middle schools scored higher on organizational structures, supportive, directive, and committed behavior, collegial leadership, principal influence, and resource support. High-performing schools scored higher on collegial behavior. No significant differences were found in institutional integrity, teacher affiliation, academic emphasis, instructional practices, and restrictive and disengaged behavior. This study helped to determine if low-performing middle schools and high-performing middle schools differed in school climate and health, organizational structures, and instructional practices. (Contains 7 tables.)