Worldwide, most children face marginalization and societal inequities to varying degrees. For developmental science to have both scientific and societal value, scientists must account for the impact of societal inequities, regardless of the focus of their research. In this article, we illustrate how equity and justice are relevant for all children. We also argue that equity and justice are essential components for all developmental science and should be the basis for how we evaluate scientific rigor. Ignoring equity and justice issues perpetuates biases within the field and limits our understanding of developmental processes. We offer graduated recommendations for all developmental scientists to consider, starting with minimal standards for inclusion and descriptions of participants, and continuing with guidance for articulating what mechanisms lead to observed differences. We also urge researchers to examine why and how social inequities and contexts shape their focal domain of developmental science.