The Baltic Yearbook of International Law is an annual publication containing contributions on topical issues in international law and related fields that are relevant to Baltic affairs and beyond. In addition to articles on different aspects of international law, each Yearbook focuses on a theme with particular importance to the development of international law. Volume 3 contains contributions that were presented at, or inspired by, the conference entitled Reparations to States, Groups and Individuals: Implementation of State Responsibility organised on the occasion of the inauguration of the Yearbook. Undoubtedly, there are many difficult legal and political questions surrounding the implementation of the law of State responsibility and this volume addresses only some of them. The contributions disclose several fundamental questions concerning the implementation of State responsibility. Can or should the general principles of State responsibility such as the obligation of full reparation be modified when applied within a specific framework of a treaty regime? Can or should these principles be modified when a treaty embodies rights that are generally considered to have achieved the character of jus cogens norms? How to enforce the obligation of reparations between States when one of them does not recognise any such obligation? One way or another all articles published in this volume raise the issue of ways and means to ensure the compliance of States with their international obligations and their responsibility in case of violations of these obligations.