Does political representation increase political participation? Analyzing a natural experiment from Mexico, in which a political party uses lotteries to select and nominate candidates for national public office, this paper presents new insights into how descriptive representation shapes the political participation of underrepresented segments of society. I find that electoral participation in the subsequent elections is significantly higher among constituents who have been represented by randomly selected deputies who closely resemble their constituents in terms of their social background and who are embedded in local organizational networks. Furthermore, I find evidence that these represented constituents feel more empowered and that the party that provides this `grassroots' representation is rewarded, receiving significantly more electoral support in the subsequent election and gaining a strategic boost over its electoral competitors. The findings highlight the importance of descriptive representation for political mobilization and have important implications for debates about democratic inclusion and representation.