In a recent meta-analysis, researchers Lynch, Hill, Gonzalez, and Pollard found that instructional improvement programs — an approach combining professional learning and curriculum or instructional materials — had a positive impact on student outcomes. The impact was greater than either professional development or introducing new materials alone. Amidst a lot of discussion about whether a focus on instructional materials or professional learning is more effective, this meta-analysis offers a productive step forward by showing that strength lies in the combination of approaches. A meta-analysis, conducted by pooling the findings of multiple randomized controlled trial or quasi-experimental studies to determine the average effect across multiple studies, can eliminate particularities of individual studies, such as those conducted in unique school settings or with a specific set of