Using a retrospective longitudinal design, this study examines school performance and social adaptation of a large sample of first, third, and sixth graders from disadvantaged neighborhoods who completed either a full-time or a half-time kindergarten program. Our objective is to compare the benefits of both kindergarten policies, which differ in program dosage. Results indicate that beyond the influence of personal characteristics, children from disadvantaged neighborhoods in full-time dosage do not perform better and do not show higher levels of social adaptation. These results are discussed within the context of other findings addressing the same objective and underscore how little we really know about the advantages of this costly policy.