This paper reports key findings from a four year study of cross-sector collaborative R&D projects in Australia testing a theoretical model formulated to explain partner collaboration experience and perceived project success. The study contributes to the understanding of knowledge-intensive collaborations, and indicates how their benefits can be sustained under conditions of high uncertainty. The study was of cross-sector collaborative projects within the Australian Cooperative Research Centre (CRC) Program which involved multiple partners and which focused on the commercialization of R&D. The model was empirically tested through a survey of project leaders and the results provided support for the three main effects hypothesized. The theoretical, methodological and pratical implications of the study's findings for the field of interorganizational relations (IOR) are discussed, and a new construct of project management competence is proposed as a determinant of positive partner experiences and the project level. This study adds to the growing body of work on interorganizational collaborative arrangements by providing systematic empirical support for the theoretical model of cross-sector R&D collaboration at the project level and at the completion or near completion phase of project development.