The heart of any trade union is its reps and activists organising in the workplace. After years of membership decline across sectors, a renewed recognition of this essential fact is behind the 'turn to organising' in the union movement today. This turn to collective organising builds strength at a local as well as a national level, and also aids in mobilising around a wider range of political issues from campaigning against austerity to taking action for the environment. In recent years, this fusion of workplace organising and national campaigning has been exemplified by Europe's largest education trade union, the National Education Union (NEU). In Lessons in Organising, the authors bring together activist, academic and union official perspectives to assess the potential (and the limitations) of the 'turn to organising' and set out the case for a new transformative trade unionism for the 21st century.