Why would a social movement aim to access seats in parliament? What happens when members of social movements win seats in parliament? How does the type of regime and party system influence the strategies of social movements inside parliament? In what way do the goals of a social movement influence the roles played by parliamentarians who are members of the movement? In his talk, Federico Rossi will focus on social movements’ pursuit of parliamentary representation, a topic that presents a crucial theoretical puzzle for social movement studies because it shows how movements employ both contentious and institutional strategies. In addition, the expansion of the legislative arena produced by the incorporation of movements in parliament adds a new dimension to the formalistic and party politics–based literature on legislative studies.