With a view to better assessment of the roles played by social security and social policy in determining well-being, this article introduces the “decommodified security ratio” (DSR), an instrument for evaluating an important duty of the social State, namely to maintain and improve people's economic security. To that end we describe the conventions for its use, analyse its main components in 20 European countries in 2002 and simulate the changes in it produced by ten variations in those components. From an analysis of the sensitivities of economic security we then demonstrate three different rationales.