This report summarizes a review of rigorous research studies on increased learning time. Findings across studies have been combined using meta-analysis techniques. - Increased learning time programs improved literacy and math achievement when instruction was led by certified teachers, though the effects were small. - Effects varied by type of instruction. Programs that used a traditional instruction style improved literacy and math achievement. Programs that used an experiential learning instruction style improved student social-emotional skills. In both cases the effects were small. - Increased learning time improved the literacy achievement of students performing below standards and the social-emotional skills of students with attention deficit/hyperactivity disorder. (author abstract)