Environmental agreements represent voluntary coalitions which mostly regulate emissions and the exhaustion of natural resources. The analysis of why and under which conditions countries (or policy makers) may be inclined toward ratifying such agreements or not has been the focus of a body of theoretical work at the interface of environmental economics and the economics of coalition games. Traditional theoretical work predicted that environmental agreements are hard to sustain due to the lacking enforceability of associated contracts and the incentive to free-ride. This hypothesis is at odds with the enormous surge of such agreements in reality over the last few decades. Recent work by Rose and Spiegel (J. Money, Credit Bank. 41:337-363, 2009) suggests that environmental agreements will be signed and are stable, because they work as a signal and help economies to get access to export (and possibly other) credits. Hence, the reason for a ratification of such agreements is their interdependence with other policies, especially ones that are related to international business. This paper sheds light on the determinants of multilateral environmental agreement (MEA) participation. In particular, we pay attention to the role of a country's international openness by means of chosen trade and investment policies for such participation. The results support the view that wealthier countries with a strong inclination towards trade and investment liberalization are more in favor of commit-P. Egger ( )