Political science research, especially in recent times, has recognized the centrality of party and executive leaders and their individual characteristics. The attention has been mostly directed towards individual leadership. However, one-chief leadership is not the only existing model of party governance, and some recent developments seem to have put forms of collective leadership into the spotlight. Two parties that have recently achieved remarkable electoral results, the Italian Five Star Movement and the German Alliance 90/The Greens, can be considered examples of alternative...