Adolescents' academic achievement goals are associated with their perceptions of teacher and peer goals. Earlier research focused on perceived teacher goals, mostly disregarding perceived peer goals' effects. However, since peer-group influence becomes prominent during adolescence, research on students' perceptions of both peer and teacher goals should contribute to understanding achievement goals. Our main hypothesis was that perceived peer goals mediate the relationship between perceived teacher goals and students' achievement goals. The research comprised three independent studies: a pilot study (N = 183) validated a measure of perceived peer goals adapted for this study. Study 1 (N = 122) found that perceived peer goals explained more variance in students' achievement goals than did perceived teacher goals. Study 2 (N = 415) showed that perceived peer goals fully mediated the relationship between perceived teacher goals and students' achievement goals. These results demonstrated that the simultaneous examination of perceptions of peers and teachers enhances our theoretical understanding of significant others' goals' relationships with student achievement goals. Researchers and practitioners may benefit from considering the interdependence between social and academic aspects of motivation in classrooms.