There is a common assumption that Western European small states are particularly active in the field of peace promotion and peacebuilding. This assumption is based on the historic track record of these states as well as their current activities in the realm of international peacebuilding. Indeed, an overview shows that small states in Western Europe invest significant financial resources and political capital into the promotion of peace in their foreign policies. Historically, such engagement could partially be explained as a survival strategy of the respective countries. However, this explanation is no longer valid today, as small states do not face existential threats from their neighbors anymore.  Thus, the “peace activism” of states, such as Austria, Denmark, Finland, Ireland, Norway, Sweden, and Switzerland poses a puzzle. While all small states in Western Europe have some form of peace policy, the magnitude of this engagement as well as its specific characteristics are different. Thus, some states focus on civilian peacebuilding, while others participate in military peacekeeping operations; likewise, some states prefer unilateral actions to promote peace, while others emphasize multilateral engagement. Given the similarity of their geopolitical position, this difference represents a subsidiary puzzle in the context of the foreign policies of small states in Western Europe.The project seeks to explore the puzzles pertaining to the peace policies of small states in Western Europe. It addresses the historic and contemporary reasons for the peace engagements of small states as well as the factors that account for the difference between various forms of engagement. As such, the study aims to contribute to the literature on peacebuilding (by elucidating the motivations of peacebuilding actors) as well as the literature on small states and foreign policy more generally.