Using migration as an example of a complex social challenge this thesis principally asked how those working in a complex interorganisational collaboration perceived the role of interorganisational trust as one of the relevant enabling factors. A qualitative case study approach was employed focusing on Partnership Skåne, a social innovation addressing migration in southern Sweden. The research concluded that interorganisational trust was perceived as playing a critical role in the functioning of Partnership Skåne, which supported existing theoretical concepts. The presence of trust was perceived both implicitly and explicitly and to some, trust was only evident when it was missing. Other factors such as relationships, leadership and organisational structure, were also perceived to be relevant to the functioning of Partnership Skåne. This thesis has contributed to the empirical research by exploring the perceived role of interorganisational trust and other factors in developing a cross-sector and multi-level collaboration in southern Sweden. This collaboration addresses a current and urgent sustainable development challenge that is also being faced at a national and international scale. Further study has been proposed using longitudinal and multiple case studies to be able to build on the findings of this research and provide further insight into the dynamic and emergent nature of the factors, which are relevant for enabling interorganisational collaborations that address complex sustainable development challenges.