Abstract
The magnitude and complexity of the different processesof decentralization that took place around the world in the last five decades, involving all types of states (unitary and federal, as well), has challenged the concepts and the traditional distinction among the forms of the States. Therefore, to get a more complete and comprehensive idea of the whole phenomenon it is necessary to return to a theoretical discussion about decentralization and this requires also comparative studies between federal countries and unitary countries.With this background, the aim of this paper is twofold: first, it discusses some concepts surrounding the idea of decentralization and the different aspect it encompasses; second, it measures and compares institutional and fiscal decentralization in two countries with verydifferent institutional settings, Argentina and Denmark, through six indicators, in order to explore some causal explanations of the role of subnational units in the process of decentralization.