The importance of building alliances based upon shared community and trade union interests is a theme with resonances from the history of community development, both in Britain and beyond. This chapter starts by summarising the lessons from previous approaches to building such alliances. The issues arising have even more relevance for community development workers in the contemporary context, the chapter argues, drawing on the findings from the authors’ work by way of illustration. The chapter then moves on to explore the experiences of the two largest trade unions in Britain: UNITE and UNISON. Both have their successes to share. Both have also faced challenges, however, illustrating some of the tensions inherent in building alliances between organisations and movements with differing histories and cultures. The chapter concludes by summarising the implications for building solidarity and developing alliances based upon mutual trust and understanding, rooted in shared values for social justice.