Abstract
This paper analyses, estimates, and compares four prototypic models of innovation, from a simple technological model to an elaborated institutional model that includes financial, organizational and technological variables. The comparison of the four models shows that institutions, in particular the national system of innovation, and organizations matter. Networks and information flows from different economic actors add to the explanatory power and give the best model fit. The empirical analysis is based on the second Community Innovation Survey Studies (CIS II) of the European Union.