My research examines the nature and impact of students’ achievement motivation, or reasons for trying in school. Specifically, I aim to (1) document motivation trajectories across development, (2) explore personal and situational mechanisms through which motivation changes, and (3) design interventions tailored to the individual and learning context. Much of my research employs person-oriented analyses, which I use to understand students’ motivation and inform how interventions can be customized to meet students’ unique needs. I am also interested in how friends influence adolescents’ motivation, engagement, and achievement in school.