Abstract
This paper aims to add evidence on the role played by firms' technological competencies in the determination of their intensity of cooperation with other firms. Using a database composed by patents jointly filcd by two or more firms in the European Patent Office, the paper confronts the hypotheses of complementary or substitutive character of technological cooperation in relation to intra-mural R&D. The results suggest that more technologically and productive specialized firms are more likely to cooperate and find no support for the hypothesis that greater level of R&D expenditure will induce greater reliance on technological cooperation. It is also suggested that firms cooperate with partners that hold cotilplenientary competencies.