This chapter examines how institutional responses to extremist right-wing parties affect their local organizational development. Institutional responses to extremism are usually subsumed in scholarly analyses of how democratic states use “militant democracy” to deal with actors threatening their democratic foundations. The first section of this chapter reviews this work to generate expectations about the effects of militant democracy policies on the organizational development of political parties. Whereas scholarly work on militant democracy tends to focus on outright bans of political parties by judicial authorities, this book adopts a broader definition to include a wider range of institutional responses and to examine how these responses affect central party organizations and then trickle down to party subunits. The second section examines the responses of the Greek state to the Golden Dawn (GD). It naturally focuses on the years before and after the arrest and criminal prosecution of the party leadership in 2013. Going beyond this judicial process, it also examines the varying responses of other institutional actors – police and municipal authorities – to the GD. The third section examines how state intervention affected the local organizational development of the GD.