Robert Kagan has been at the forefront of sociolegal research into regulation for more than thirty years. His work addresses in general the extent to which law fosters or impedes economic activity, and the conditions under which people and organizations both comply with the law and sometimes fail to comply with it. This article analyzes his contributions and suggests some questions for further inquiry prompted by Kagan's work. The survey takes as its starting point Kagan's books Regulatory Encounters (ed. with Axelrad 2000) and Shades of Green (with Gunningham and Thornton 2003), before going on to consider his more recent research, which probes in some detail into the impact of enforcement and the ideas of compliance and deterrence.