The aim of this study was to examine how mathematics tracking in high school (i.e., the practice of grouping students into basic or advanced sequences of courses) shapes students' perceived competence and their perception of the usefulness of their math courses. We hypothesized that the socioeducational environment of the math classroom (i.e., students' perception of different teaching strategies) would play an important role in this process. Participants were 732 high school students (41% boys, 59% girls) who completed questionnaires on motivation and classroom environment before (Time 1: second year of high school, mean age = 13.71, SD = 0.80) and after (Time 2: fourth year of high school, mean age = 15.71, SD = 0.80) math sequence placement. Although placement in an advanced sequence was associated with reduced perceived competence, it predicted positive changes in perceived competence when it acted initially on classroom discipline (mediating effect). Moreover, teaching strategies that emphasized classroom discussion and support for investigation fostered student motivation, particularly for those placed in a basic sequence (moderating effect). These results confirm the hypothesis that the classroom environment contributes to explain the tracking effect on student motivation.