664 relatively low achieving first grade children were recruited into a longitudinal study. Measures of peer academic reputation (PAR), peer acceptance, teacher-rated academic engagement and achievement, and reading and math achievement were obtained in Year 2, when the majority of students were in second grade, and 1 year later. Measures of academic self concept were obtained in Year 1 and in Year 3. As young as second grade, children's perceptions of classmates' academic competence were distinct from their perceptions of peers' other social and behavioral characteristics. SEM analyses found that Year 2 PAR predicted Year 3 teacher-rated academic engagement and reading (but not math) achievement test scores, above the effects of prior scores on these outcomes and other covariates. Furthermore, the effect of PAR on academic engagement and achievement was partially mediated by the effect of PAR on children's academic self concept. Implications of these findings for educational practice and future research are discussed. (Contains 2 figures and 4 tables.)