In today's dynamic world, organizations have to deal with incompatible institutional demands that arise as the result of different institutional logics and work within such institutional complexity so they can survive and function. Research on how organizations address institutionally complexity is emerging but still rare (Greenwood, Raynard, Kodeih, Micelotta & Lounsbury, 2011). This dissertation aims to help fill that gap in the literature, especially by showing what kind of work is required in institutionally complex settings to create social change, how temporal complexities are managed, and how organizational design-based responses are created for dealing with institutional complexity with four empirical papers that study Cross-Sector Partnerships (CSP). Situated as it is within the theoretical field of institutional complexity and work, this dissertation contributes to the formulation of a new perspective on how institutional complexity is managed and how change occurs in institutionally complex settings. It also adds to grand challenges debate by studying CSPs addressing gender inequality and global health problems.