This article examines the professionalization process of universities through their adult education practices. It does so in a comparative way, between Quebec and France, two apparently contrasted situations. Following the societal analysis and the methods of the sociology of public policy categories, the analysis distinguishes two specific development paths for the university education supply addressing adult demand. While revealing the societal categories of lifelong learning, this method allows us to be attentive to what connects them as much as what depart from them. The article demonstrates that the professionalization of the universities engages a system of conventions, specific in each society by a local and historical configuration of action, between the University, the State, Socioeconomics partners and Individuals going back to study and/or at work.