This longitudinal study adopts a multidimensional perspective to examine the relationships between middle school students' perceptions of the school environment (structure support, provision of choice, teaching for relevance, teacher and peer emotional support), achievement motivation (academic self-concept and subjective task value), and school engagement (behavioral, emotional, and cognitive engagement). Participants were from an ethnically diverse, urban sample of 1157 adolescents. The findings indicated that student perceptions of distinct aspects of the school environment contributed differentially to the three types of school engagement. In addition, these associations were fully or partially mediated by achievement motivation. Specifically, student perceptions of the school environment influenced their achievement motivation and in turn influenced all three types of school engagement, although in different ways. Moderation effects of gender, ethnicity, and academic ability were also discussed.