Over the past two decades, a number of multistakeholder certification schemes have emerged and become particularly vibrant sources of nonstate governance. We know a great deal about the conditions that help to explain how these certification programs emerged and evolved within and across sectors, but much less about their direct effects and broader consequences. Using the Marine Stewardship Council (MSC) as a case study, this chapter examines how we can evaluate the effectiveness of nonstate certification programs and discusses what certification in the fisheries sector has taught us.