In the initial stages of university-industry collaborations (UICs) the chosen form of the collaboration and how potential collaborators are approached strongly influence their development and success. We investigate how the mode of initiation of UICs depends on firms’ objectives to build economic, intellectual and reputational capital. We argue that: (i) capital building is not just an outcome of successful UICs, but an objective that influences firms’ behaviour from the start, and (ii) firms’ subjective evaluation of the effectiveness of interaction channels acts as a mediator between intention and behaviour. Our empirical analysis, building on a survey of 190 UK-based firms, shows positive associations between: economic capital-building objectives and institutional mode of initiation, mediated by the perceived effectiveness of knowledge acquisition channels; reputational capital-building and individual mode of initiation, mediated by the perceived effectiveness of knowledge co-creation channels; intellectual capital-building and both institutional and individual modes, mediated by the perceived effectiveness of, respectively, knowledge acquisition and co-creation channels (the latter when the firm intends to build new intellectual capital, the former when it intends to exploit existing capital). Our findings offer practical implications regarding how firms and universities should initiate interactions depending on the firms’ objectives.