Health system strengthening (HSS) comprises the strategies, responses, and activities that are designed to sustainably improve country health system performance. Social and behavior change (SBC) programming is an approach that applies systematic insights about why people behave the way they do, and how behaviors change, to effect positive outcomes for and by specific groups of people. But what is the role of SBC within HSS programs? This document identifies the ways in which the behavior of health system actors has a direct impact on the strength of the overall health system and on health outcomes. It highlights how SBC may be integrated into HSS programs to strengthen HSS program implementation and measurement, and improve the system’s ability to support the practice of healthy behaviors.