Critical theory is a conceptual, theoretical, and methodological framework for understanding society. It scrutinizes the role of power, inequality, and marginalization across varied contexts. Though often an umbrella term that includes other nuanced theories around particular demographics, critical theory offers guidance on both how to approach research on out-of-school learning programs and the ways to address topics of equity within these programs’ designs. This entry discusses the development of critical theory, how critical theory incorporates a reflective stance, the various forms of critical theory, and how critical theory can inform both research on out-of-school learning and models of out-of-school learning.