The best way to understand Open Innovation is to look at how top-performing companies actually apply it and, even more importantly, how their approaches have evolved and continue to evolve. This chapter analyzes 15 case studies that showcase the concrete implementation of Open Innovation and the emerging models of corporate-startup collaboration. Particular attention is given to the most recent trend toward hybrid approaches. We explore the models and modes adopted, the strategic objectives pursued, as well as the challenges encountered along the way.