This study compares five middle schools with the IB MYP and five demographically similar middle schools without the MYP. All ten schools come from the same large, socioeconomically diverse, public school district comprised of rural, urban, and suburban communities in the U.S. Analysis was conducted of student engagement and performance, student and parent perceptions of school climate, and principal interviews from each school. In analyses of performance and engagement, differences were controlled for race/ethnicity, receipt of Free and Reduced-price Meal System services, receipt of special education services, enrollment in English for Speakers of Other Languages classes, gender, and when possible, previous test performance. Some evidence was suggested of improved performance in mathematics and science for MYP students. Ratings of student engagement, for the most part, were similar for students in MYP and comparison schools. Overall rating of school environment, however, was higher for MYP students, and a higher percentage agreed that "Overall, I feel good about being in this school". All 5 MYP principals noted interdisciplinary learning as a positive influence, and 4 identified teacher training and the support of the MYP coordinator as important benefits. Findings suggest the following recommendations: Continue to examine the performance of MYP students through their years of participation in the program, survey students with questions directly addressing their experience in MYP, solicit feedback and input from teachers in MYP schools, and assess teachers' perceptions of the MYP training.