We mobilize the literature on third-place to analyze how various actors, who are not used to working together, have been able to go beyond institutional tensions to develop social innovation (a collective and connected housing for seniors) and demonstrate their actorhood. We study one exemplary case through the elaboration of an analysis grid (social environment, community life, and partial organization) to observe the organizing of a ephemeral third-place. Our empirical analysis led us to mobilize the concept of organizationality to understand the levers that enabled the ephemeral third-place to foster innovation despite its structural weakness: the strength of design thinking as an alternative method of co-construction of knowledge, the construction of a common cause, the recognition of a legitimacy to act, the management of the social and temporal boundaries of the place. The identification of these levers enriches the concept of organizationality. JEL Codes: O310