This paper systematically reviews the evidence on interventions, initiatives, and policies to increase school meal participation in the United States. Four electronic databases were searched (PubMed, Academic Search Ultimate, Education Resources Information Center, and Thomson Reuters’ Web of Science) to identify peer-reviewed and government studies conducted in the United States and published in English through January 2022. Qualitative studies; studies focused on snacks, afterschool meals, or universal free meals as the sole exposure; and studies conducted in schools not participating in the federal school meal programs or outside of the school year were excluded. Risk of bias was assessed using an adapted version of the Newcastle-Ottawa Scale. Articles were grouped according to type of intervention or policy and were narratively synthesized. Thirty-four articles met inclusion criteria. All studies examining alternative breakfast models (eg, breakfast in the classroom or grab-and-go breakfast) and restrictions on competitive foods found increases in meal participation. There is also some evidence that stronger nutrition standards do not negatively impact meal participation and, in some cases, may promote meal participation. There is limited evidence on other strategies, including taste tests, modified menu options, changes to the meal period length, changes to the cafeteria environment, and wellness policies. There is evidence that alternative breakfast models and restrictions on competitive foods promote meal participation. There is a need for additional rigorous evaluation of other strategies to promote meal participation.