Social regulation is ubiquitous in the US healthcare system, and American healthcare organizations claim to be among the most regulated institutions in the world. Yet relatively little is known about the impact of social regulation on these organizations' performance, or about the characteristics or determinants of effective regulatory strategies and approaches. This paper explores the use of social regulation in US healthcare, drawing on the wider literature on regulation in other countries and settings and on the growing body of general regulatory theory. It offers a framework for analysing and comparing regulatory arrangements, presents the findings from an exploratory qualitative study of regulators and regulated organizations, and concludes by developing a framework of the emergent characteristics of effective regulation which might be used in future evaluations of healthcare regulation.