London Citizens is a "Broad Based Community Organization" allying member institutions representing faith institutions, universities, schools, trade unions and community groups across London. Since 1996 it runs campaigns in different fields such as housing, jobs, poverty, safety, environment and immigration. London Citizens is recognized as a countervailing force in the city's and country's governance. The organization tries to professionalize its activity while staying grass root. But since the election of Obama, who famously started his political career as a community organizer in Chicago, the brand "community organizing" is highly fought for. In 2010, a key part of the Coalition's vision for the Big Society is the training of community organizers. This paper will analyze the mechanism of this professionalization and its stakes. It will study the interaction between Citizens UK and the Big Society program. It will argue that not only the origin of community organizing as a profession but also the passion fueled toward it, have made it an ambiguous term.