This article presents the findings of a study examining the roles and behaviours of boundary-spanning managers during the establishment of voluntary public-private partnerships (PPPs). It responds to recent calls in the literature to pursue research that incorporates the pivotal contribution of individual actors in the collaborative process, and to set this research within the stage specific context of partnerships. The analysis is located within the theoretical framework of organizational sensemaking. Using a grounded methodology of data collection, coding and analysis within ten Australian and UK PPPs, the study demarcates a four-stage evolutionary establishment process of PPPs. Within each stage there exists a specific managerial focus in conjunction with one or two main managerial challenges. Boundary-spanning managers employ various strategies to overcome such challenges within each specific stage, thus ensuring the progressive evolution of the PPP. These foci, challenges and strategies are identified and analysed in the article.