In this article, we review research on the outcomes of diverse reading programs on the achievement of struggling readers in elementary schools. Sixty-five studies of 51 different programs met rigorous standards. Eighty-three percent were randomized experiments and 17% quasi-experiments. Outcomes were positive for one-to-one tutoring and were positive but not as large for one-to-small group tutoring. There were no differences in outcomes between teachers and teaching assistants as tutors. Whole-class approaches (mostly cooperative learning) and whole-class/whole-school approaches incorporating tutoring for struggling readers obtained outcomes for struggling readers as large as those found for all forms of tutoring, on average, and benefited many more students. Technology-supported adaptive instruction did not have statistically significant positive outcomes for struggling readers, however. In agreement with findings of previous reviews, in this synthesis, we found that substantial impacts can be obtained for struggling readers, with interventions aligned within a Response to Intervention network.