This chapter reports on an action research case study of integrated obstetric care in the Netherlands. Efficient and patient-friendly patient flows through integrated care networks are of major societal importance. How to design and develop such interorganizational patient flows is still a nascent research area, especially when dealing with a large number (n>3) of stakeholders. We have shown that a modification of an existing method to support interorganizational collaboration by system dynamics-based group model building (GMB) (the Renga method, Akkermans, 2001) may be effective in achieving such collaboration.