This article explores some of the key institutional challenges hindering the development of a new ‘social’ housing cooperative model in Finland. In response to rising housing unaffordability and insecurity in the private housing sector, and a retrenching social housing sector, Finland is experiencing a resurgence of practical and political interest in housing cooperatives. Based on a document study and interviews with key stakeholders, this paper investigates three Finnish housing cooperatives, all of which are part of a broader state-subsidised pilot study. Despite different operational dynamics across projects, in this paper we identify three overarching ambiguities in Finnish land and housing policy which are hindering their development. Firstly, despite support from public authorities, cooperatives are difficult to categorise within existing social housing frameworks. Secondly, due to temporally-restricted regulatory instruments, authorities are also sceptical of their long-term affordability. Tying these together, we suggest, is also a further third factor. Namely that, due to its entrepreneurial real estate policy, the City of Helsinki refuses to lease land under market rent to housing cooperatives. Contributing to international scholarship on the public-cooperative nexus, this article investigates the impacts these institutional ambiguities and contradictions can have on contemporary housing cooperative developments.