Researchers conducted a comprehensive search of educational databases and clearinghouses and found more than 1,600 reports on the implementation and outcomes of arts integration interventions since 2000. After further screening to identify studies with Pre-K through Grade 12 outcomes, 135 reports were reviewed by What Works Clearinghouse-certified reviewers. Reports were then classified according to definitions of ESSA tiers of evidence. To gain a fuller picture of arts integration research findings across all well-designed studies, researchers recorded the magnitude of effects from 27 studies of interventions and meta-analyzed those effect sizes.