Open firms are not equally successful. This is because, in order to benefit from external sources of knowledge, firms must be able to absorb such knowledge. The paper outlines a firm's context as a set of organizational and social features, which may be considered absorptive capacity antecedents. It explores the mediating role of such antecedents in the relationship – hitherto insufficiently researched – between the degree of openness and innovative performance. The use of a methodology combining both direct interviews and survey of Italian firms has allowed us to confirm the supposed mediating role. We also identify different modes for companies to open up their innovation process and, for each of them, the antecedents that are consistent with choices regarding the degree of openness