As an alternative to traditional housing development that has self-management, codesign and resident participation at its core, initiating cohousing groups often struggle to be recognised by traditional housing institutions. They can also lack the social, technical and financial expertise required to articulate needs or bring projects to fruition. When mainstream development partners (e.g., architects and housing associations) are involved, they too may misunderstand fundamental risks and issues related to self-managed housing groups. These knowledge gaps are addressed by either hiring external development consultants, programme managers and financial and legal advisers, or involving novel professions catering to cohousing particularities such as group-facilitators, process-management and legal coop-specialists. The expertise of these ‘professional activists’ is often (initially) based on personal experience living or developing their own group, rather than formal training. This paper will draw on interviews carried out with cohousing professionals and advisers in the Netherlands, France, the UK and US to: (a) look at the specific needs and emerging offer of professionals, training and networks in each country and (b) identify major dilemma’s and risks connected to different fields of expertise and to the process of ‘becoming’ professional, including: credibility and objectivity, exploitation and power dynamics, and commercialisation and monopolisation. We conclude with a discussion about how the move to ‘professionalise co-housing’ is connected to key questions and debates around ‘the need to’ mainstream and institutionalise this alternative sector according to particular logics. We ask what successful professionalization looks like and describe new paradigms for collaboration in housing provision and management.@en