BACKGROUND Play is essential for child growth and development, and may have academic and social-emotional implications. To understand the relationship between in-school play opportunities and academic achievement (AA) and social-emotional well-being among elementary school students, a systematic review of the current in-school play literature was conducted. METHODS Keywords were input across 7 search engines. After screening, 20 peer-reviewed publications related to play, AA, and social-emotional well-being met the inclusion criteria for this review. FINDINGS Across the included publications, recess was the only in-school play opportunity assessed. Overall, student behavior and social-emotional outcomes benefited from more recess while mixed results were found between recess participation and academic outcomes. However, more recess was not detrimental to AA. CONCLUSION The findings from this review support the need for recess as part of a whole child approach to education that may mitigate the negative outcomes of sitting through long periods of instruction. More research is needed on the AA and social-emotional effects of other types of in-school play opportunities (ie, centers, play stations, and other breaks). Findings from this review indicate that recess is a necessary part of the elementary school day.