Political parties rely on youth wings for the political representation and mobilisation of youth. This article examines the role of youth wings within political parties; youth wing members assess the role that their organisations play in promoting youth political representation in their mother parties. Empirically, it draws on 58 semi-structured interviews with high-ranking Portuguese youth party members, comparing the perspectives in parties with and without autonomous youth wings. It assesses the role of youth wings in shaping parties' policy platforms (substantive representation); in promoting young candidates for public office (descriptive representation); and in mobilising youth to political participation. Overall, youth wings emerge as a double-edged sword. While they ensure youth representation in party bodies, they also often lead to their de facto internal segregation. In this context, youth wings' ability to influence internally, both in terms of policy and candidate selection, hinges on informal networks and negotiations with mother party leaders. Youth wings are also perceived as not being effective in mobilising youth to parties, with those who join youth wings expressing more office-seeking goals than those who join parties without these structures.