Today there is no doubt that mergers have permeated all sectors of society, both private and public, including the healthcare sector. However, the knowledge of mergers in healthcare is highly uncertain and scarce. Very little research has been done on mergers of university hospitals and because of a continuing merger trend in healthcare, it is clear that more research is needed. This award-winning Ph.D. thesis explores one of the largest hospital mergers ever made: the flagship merger between the Karolinska Hospital and the Huddinge University Hospital in Stockholm, Sweden. The aim is to increase our understanding of the pitfalls and possibilities in merger processes at large and complex organizations, especially in professionalized, public service settings.