Background: The role of support workers in self-advocacy groups is complex. The lack of transparency about who controls the agenda within groups is problematised by commentators but the evidence is limited about how supporters act, exercise power and are regarded by self-advocates. Aim: This study investigated the work of supporters in independent self-advocacy groups and how their work was understood by members. Method: Grounded theory methodology was used. Semi-structured interviews were conducted with 25 members of 6 independent self-advocacy groups, in Australia and the UK, and 10 supporters. Results: Supporters had three roles: supporting empowerment, managing operations, and leading strategic planning. They exercised power, controlling many group activities, but did so in ways that enabled groups to flourish, and scaffolded members' sense of control. Conclusion: Supporters shaped groups, developing and resourcing them while promoting empowerment and enabling self-advocates to perceive partnerships; regarding supporters work as complementary to their own.