Within the framework of the evolutionary theory of technologicai change, recent empirical research has highlighted the existence of multiple forms of articulating firms’ innovation processes. We have made a previous study of this topic and have managed to identify various technologicai patterns in the determination of which an important role is played by both the expressive variables of firms’ structures and hose corcerning technological activity and its innovatory results. Following a recent research effort devoted to the evaluation of the technological policy of the Centro para el Desarrollo Tecnológico Industrial (CDTI), under the aegis of which a wide sample of Spanish innovating firms were surveyed, we have once again found evidence of the existence of differentiated behaviour patterns among these firms. On the basis of the information compiled in that survey, ouí aim has been to analy the factors which determine the innovating behaviour of firms which develop R&D projects, on a regular basis, in contrast with those whose technological activity is more sporadic. We also provide a description of the most important aspects of the behaviour of innovating firms. Tko bgit models are then estimated to specify the factors determining the differences in behaviour among firms who carry out R&D activities with a greater oí lesser.

Keywords: technological innovation, R&D, pattems of behaviour.