The focus of this article is on multi-organizational cross-sector social partnerships (CSSP), an increasingly common means of addressing complex social and ecological problems that are too extensive to be solved by any one organization. While there is a growing body of literature on CSSP, there is little focus on collaborative strategic management, especially where implementation and outcomes are concerned. This study addresses these gaps by offering a conceptual model of collaborative strategic management, which is then tested through the use of two qualitative empirical cases of collaborative regional sustainable development strategies (CRSDS). The model augments previous collaboration models by highlighting two levels of implementation (the collaboration and the organizational levels) and by considering the different types of outcomes, and the feedback loops. © 2011 Springer Science+Business Media B.V.