This article presents the results of participatory research into the roles and practices of autistic self-advocates in the Netherlands, and the outcomes of their activities. The article discusses the history of Dutch autism self-advocacy, situating it within the history and practices of self-advocacy internationally and the socio-cultural context of the Netherlands. Particular reference is made to Judi Chamberlin’s model for building effective self-advocacy organisations. Key findings include the scope of significant achievements, and the identification of barriers to efficacy in the areas of governance, personal and organisational capacity, relationships with other organisations, and coalition-building. The research concludes by considering what practices could serve to build increased capacity and efficacy, based on the experiences of these and other self-advocates.