This book examines the ways and means by which nation-states interact with their environment. The author proposes a theory of context that examines the way in which system structure, normative environment, and history can act as contexts for decision makers, either as causes, barriers, or by changing meanings. The theoretical and methodological material is illustrated by a number of case studies that apply context theory to specific problems, such as decolonization, USSR-East European relations, and enduring military rivalries.