Abstract
The aim of this paper is to analyze the determinants of the main phases of the innovation process in Portuguese manufacturing firms. The analysis will adopt as its main frame of reference an interactive model of the innovation process, on which empirical tests will be carried out, making use of tobit and probit models and simultaneous equation systems. It is broadly concluded that the relationships shown between the main variables that are typical of the innovation process in the context of Portuguese manufacturing firms are tenuous and unsystematic.