The Mermoz multi-professional health center is a healthcare practice, including 24 professionals, on the outskirts of a major French metropolis. This article presents the challenges faced from the idea to the implementation of an interprofessional primary care offer. The difficulty of freeing up time for the construction of the common real estate and sanitary project has been overcome thanks to powerful motivations: the desire for more interprofessionality in practices that are sometimes fragmented, the need for support in the management of complex patients, the pleasure of being a group, and the improvement of healthcare. The horizontal mode of governance enabled a health care offer adapted to the specific health needs of a multicultural and precarious sector to be combined with a place for teaching and research.