Using a methodology that both analyzes particular constitutional texts and theories and reconstructs their historical evolution, Chris Thornhill examines the social role and legitimating status of constitutions from the first quasi-constitutional documents of medieval Europe, through the classical period of revolutionary constitutionalism, to recent processes of constitutional transition. A Sociology of Constitutions explores the reasons why modern societies require constitutions and constitutional norms and presents a distinctive socio-normative analysis of the constitutional preconditions of political legitimacy.