This paper intends to develop a multidimensional measure of state legitimacy that provides original information on the interaction between a country’s polity and its social fabric. An index of state legitimacy is presented, stressing the institutional and political conditions for human dignity and human development, through the level of adherence (the legitimation process) of the people. Our approach strives to combine a universalist standpoint and a particularist view. An initial minimal threshold — related to elementary (fundamental) legitimacy — is the implementation of the “do no harm” principle by state power: how the physical integrity of all citizens is respected. Two dimensions are then considered: inherited legitimacy looks at the historical evolution of the relationship between state and society and is related to procedural fairness criteria: ways of access to power, existence of shared norms and values in society (concerning the political culture), and existence of a common language. Acquired legitimacy is related to the quality of public goods and institutions that help shape the recognition of a state by the population and deals with substantial fairness criteria: access to basic public goods (water, health, education, environment), respect of diversity/minority rights, quality of law enforcement (and fight against corruption).