The introduction of a statutory recognition procedure offers British unions the opportunity to reverse membership decline by organising non-union workers. The aim of this paper is to test theories of individual union joining in order to assess the likely impact of the new procedure on British union membership. Responses of a nationally representative sample of non-union employees to the question 'how willing would you be to join a union if one were available at your workplace?' are analysed. Results suggest that the new legislation will cause union membership to rise among manual employees, but that unions will face a much harder challenge organising non-manual employees. Unless unions can change their environment, or change themselves then long-term decline is likely.