This chapter focuses on the scholarship on epistemic communities and departs from the traditional literature on coalition formation around shared values and beliefs. It examines the case of the North American Pollutant Release and Transfer Registry Project, undertaken by the North American Commission for Environmental Cooperation. The chapter analyzes the case of the Citizen Submission on Enforcement Matters mechanism. It aims to compare the literature on transnational nonstate actors, specifically on environmental nongovernmental organizations (ENGOs). The chapter argues that knowledge sharing by North American ENGOs effectively helped bring about policy change in Mexico. It suggests that there are a number of possible pathways and new avenues of inquiry for the study of transnational environmental private regulation in North America. The chapter concludes by offering some thoughts on possible pathways and new avenues of inquiry for the study of transnational environmental nonstate-led regulatory regime formation in North America.