Industrial firms increasingly attempt to license their technologies apart from applying them in their own products. Because of the imperfections in technology markets, an active approach towards technology licensing does not automatically result in licensing transactions. To balance prior research, which has focused on licensing transactions as the outcome of licensing intentions, we take a contingency view to analyze how characteristics of a firm's innovation ecosystem determine different strategic types of licensing. Specifically, we distinguish proactive licensing, which refers to identifying recipients for technology transactions, and reactive licensing, which relates to offering licenses to infringers of a firm's intellectual property. Survey data show that environmental antecedents concerning appropriability, i.e., patent protection and technological turbulence, and determinants regarding technology markets, i.e., transaction frequency and competitive intensity, have different effects on proactive and reactive licensing. On this basis, the article has major implications for research into technology licensing, markets for technology, and open innovation. (C) 2009 Elsevier B.V. All rights reserved.