This article argues that both hard and soft institutions shape the strategies and - to a lesser extent - the preferences of political actors in the European Union. First of all, it discusses the institutional perspective in political science and presents an institutional model of decision-making. Secondly the institutional argument is illustrated by a detailed account of the decision-makingprocess with respect to the Packaging Directive. An analysis of the actor configuration, the interactions between the involved actors and an overview of the decision-making process itself, all show to what extent actor's strategies and preferences are constrained and empowerd by the European institutional context.