Is placement in special education during the elementary grades associated with higher school performance? To shed light on this question, we investigated the relationship between participation in special education programs during Grades 1-6 and school achievement among 1,234 low-income children participating in the Chicago Longitudinal Study. About 15% of the study sample received special education services (half in learning disabilities and half in other disabilities), 22% were retained in grade, and 50% changed schools more than once over the elementary grades. Controlling for school achievement prior to placement in special education, as well as for family background, school experiences, and school attributes, children receiving special education services had lower reading and math achievement scores than other children, especially during Grades 4-6. Children with learning disabilities benefited less from special education services than did children with other disabilities. Grade retention and school mobility during the primary grades were associated with significantly lower reading and math achievement above and beyond prior achievement and other factors. Continued scrutiny of special education services and retention practices, at least as they currently exist in large cities, may benefit children with learning difficulties.