Providers of K-12 in-service teacher science professional development programs (PDPs) in the United States are moving to address recent and unprecedented policymaker calls to close achievement gaps in K-12 science learning. Our systematic review of primary, peer-reviewed equity-focused PDP studies is intended to inform this movement. We structured our review around the themes of selected studies'PDP context, research design and methods, and outcomes. PDP context and research design and methods were evaluated against relevant effective practices for equity-focused K-12 in-service science teacher PDPs. The theme of PDP outcomes was structured around reported teacher and student outcomes. We use these themes to present a coherent picture of previous equity-focused PDP efforts. This picture informs discussion and selection of strategies for effective implementation of PDPsdesigned to target the needs of specific traditionally underserved student populations. It also highlights potentially promising lines of inquiry for PDP developers and researchers to pursue.