Jonathan Valdez explores the role of ideology in the maintenance and subsequent collapse of Soviet influence in Eastern Europe. He looks at how Marxism-Leninism was used to legitimise Soviet influence in Eastern Europe, to rationalise policy decisions, to communicate Soviet intent and policy desires to East European elites, and to explain change in socialist systems. The author argues that the use of the fundamental principles of Marxism-Leninism to perform various functions ultimately brought about a change in the basic assumptions of the theory itself. This resulted in the abandonment of the previous insistence on a universal model of socialism and of the idea that the international interests of the socialist bloc must take precedence over individual national interest. Soviet influence in Eastern Europe rested on little else than these ideological principles and as Valdez shows consequently stood little chance of surviving their reinterpretation.