The research presented in this thesis proposes an accounting framework for measuring the openness degree of companies’ innovation processes through the analysis of audited consolidated financial statements. Four metrics are defined, based on costs and revenues deriving from OI activities and new investments and divestments of intangibles, and combined to obtain a synthetic measure of openness. Hence, the research objectives of my PhD thesis are the following:  O1: Literature review: To review the state-of-the-art of OI research, underlying the different methods of measuring OI adoption and identifying specific categories of metrics, on the basis of how they have been operationalized by scholars.  O2: Measurement framework for OI: To design a methodology that considers the pecuniary aspects of OI practices, by focusing on the “acquiring” and “selling” models introduced by Dahlander and Gann (2010).  O3: Validation: To test the methodology with an empirical study in the biopharmaceutical industry, in order to validate both the framework applicability and its explicative power and usefulness.