Project Abstract Social determinants of health (SDOH) have critical implications for shaping health and health inequities in cancer incidence, morbidity and mortality. The Implementation Science Centers in Cancer Control (ISC3) are uniquely positioned to evaluate the SDOH that drive these disparities and ultimately identify implementation strategies to reduce them. SDOH shape the Outer Context (i.e., broader sociopolitical environment) that affect communities, health systems, and its residents. The Inner Context (i.e., healthcare systems) is uniquely positioned to identify and address SDOH to improve patient care and cancer outcomes. The purpose of this Administrative Supplement is to advance health equity through implementation science using environmental scans and cross- site collaboration. Specifically, we will (1) partner with all ISC3 centers to conduct an environmental scan of Outer Context common data elements to better understand the sociopolitical context that drives cancer-related disparities; and (2) collaborate across two Centers (Wake Forest iDAPT ISC3 and UPenn ISC3) to measure Inner Context SDOHs within cancer care delivery settings. Results from this administrative supplement will facilitate multi-site pilot implementation studies that improve the measurement and mitigation of SDOH to improve cancer care outcomes and health equity.