The authors investigated the differential effect of retention on the development of academic achievement from grades 1 to 5 on children retained in grade 1 over 6 years. Growth mixture model (GMM) analyses supported the existence of two distinct trajectory groups of retained children for both reading and math among 125 ethnically and linguistically diverse retained children. For each achievement domain, a low intercept/higher growth group (Class 1) and a high intercept/slower growth group (Class 2) were identified. Furthermore, Class 1 children were found to score lower on several measures of learning related skills variables and were characterized by having poorer self-regulation and fewer prosocial behaviors compared to the other group. Findings suggest that some children appear to benefit more from retention, in terms of higher reading and math growth, than others. Study findings have implications for selecting children into retention intervention and early intervention.