Summary: In about 950 words the entry establishes the relevance of the concept for the discipline of political science, points to various usages of the term, introduces Lehmbruch's attempt to systematize the diverse meanings, distinguishes neo-pluralistic from pluralistic theories, and ends in a discussion of what kind of normative fundament is necessary to achieve consensus. All contributors to the literature on consensus agree that no political-social unit can exist without a minimum of integration and therefore consensus. In an attempt to systematize the diverse understanding and definitions of the term, Lehmbruch's 4 categories are reviewed who distinguishes between consensus on: issues, rules of conflict regulation, authority, and multi-dimensional consensus which involves the interaction between the above mentioned objects of consensus. Open remains the question how much of what consensus is necessary to secure the unity of the social-political unit. Authors in the pluralism tradition view only rules of procedure as essential, while neo-pluralists add concrete political and social principles which the entry discusses in exemplum. The entry ends in a discussion of the ideas on what normative fundament must exist in order for consensus to be possible. Fraenkel's natural law approach and Habermas' discourse theory are contrasted. But the entry states that despite the centrality of the term many questions regarding it have not been solved.