Many countries align their environmental policy and environmental regulation by way of multilateral environmental agreements (MEAs). Previous work in economics provided insights in the economic and political determinants of MEAs at large. This paper distinguishes MEAs by the main issues covered and classifies them in five clusters: biodiversity; atmosphere; land; chemicals and hazardous wastes; and seas. Then the role of environmental, economic, and political factors and of dynamic and cross-cluster effects is studied at the level of MEA clusters. Two findings stand out from this empirical analysis. First, economic size and multilateral trade liberalisation of countries are found to be the most important drivers of MEA participation across all clusters. Second, adjustment costs turn out to deter and, in particular, cross-cluster spillovers turn out to stimulate MEA participation across countries and clusters.