TY - JOUR A1 - Helm, Carsten A1 - Sprinz, Detlef F. T1 - Measuring the effectiveness of international environmental regimes N2 - Although past research has emphasized the importance of international regimes for international gover-nance, systematic assessments of regime effects are missing. This article derives a standardized measure-ment concept for the effectiveness of international environmental regimes. It is based on a simultaneous evaluation of actual policy against a no-regime counterfactual and a collective optimum. Subsequently, the empirical feasibility of the measurement concept is demonstrated by way of two international treaties regu-lating transboundary air pollution in Europe. The results demonstrate that the regimes indeed show positive effects;but fall substantially short of the collective optima. Y1 - 2000 ER -