The year 2008 saw the 10th anniversary of the establishment of the British Trades Union Congress (TUC) Organizing Academy which was designed to train a new cadre of union officials. The aim was to develop a culture of organizing that could help to transform the decline in trade union membership by bringing in new members who had been trained to be active within their unions. Through in-depth interviews and a survey of graduates of the Academy we look at the impact this project has had on individuals, their unions, and the wider union movement. We are particularly keen to give voice to the graduates as they have been charged with the difficult task of transforming the British trade union movement. We find evidence that trained organizers continue to be influential within their unions, but that many (although by no means all) get stuck in relatively junior positions because of the lack of a specialist career structure. This inevitably constrains their influence. The division between 'servicing' and 'organizing' functions is an almost inevitable consequence of the establishment of a separate, specialist organizing role and can also cause tensions and constrain the spread of organizing practices within unions. Despite this, there is evidence of widespread adoption of basic organizing practices, although more strategic organizing is still far less common. More widely, there is strong evidence of organizers developing new and influential networks between unions, and of individual unions implementing specialist organizing training. Despite this mixed evaluation, we argue that the creation of the Academy has had a considerable impact on British unions and has fostered important and innovative organizing approaches that would probably not have emerged otherwise.