The International Law Commission, when drafting articles on nationality of persons in situations of State succession, omitted cases of unlawful territorial changes. These do not result in State succession; they may be dealt with under the rubric of State continuity. The Baltic – Russian cases show the particularly complex nature of these situations, both as concerns agreement on continuity and decisions on nationality. The author examines in detail the Citizenship Laws of the Baltic States and Russia, as well as relevant constitutional and international statements about the international legal status of the States and responses of the international community thereto. The main question addressed in the book is about solutions which States have to adopt concerning nationality of individuals in situations of State continuity, especially where States re-emerge after long years of occupation. Although the book is specific in its origin, it is of general importance because it draws conclusions concerning developments in law and practice which are relevant for a better understanding and regulation of nationality and statehood in international law.