Besides acquiring external knowledge, many firms have begun to actively commercialize technology, for example, by means of out-licensing. This increase in inward and outward technology transactions reflects the new paradigm of open innovation. Most prior research into open innovation is limited to theoretical considerations and case studies, whereas other lines of research have focused either on external technology acquisition or exploitation. In an integrative view, we consider inward and outward technology transactions as the main directions of open innovation. Moreover, technology aggressiveness, which constitutes an important dimension of technology strategy, is identified as a major determinant of open innovation. Data from a survey of 154 industrial firms are used to test three hypotheses relating technology aggressiveness, external technology acquisition, and external technology exploitation. In addition, clusters of firms with homogeneous strategies regarding technology aggressiveness and open innovation are identified.