This cumulative PhD dissertation studies the political inclusion of young men and women in democratic and democratizing states. It compares three aspects of political inclusion on the macro, meso, and micro levels of analysis: quotas, parties, and elections. The articles in the dissertation ask where and why states adopt quotas for youth, how parties implement the regulations, and how young candidates' age impacts their electoral performance. With its focus on youth, the dissertation explores the under-representation of a group that has, so far, received little scholarly attention. While existing research has focused on describing and explaining cross-national patterns of political youth representation, this dissertation aims to unpack processes and factors leading to representational outcomes. It does so by focusing on the entry and inclusion of youth into politics, which, arguably, precede and condition their descriptive representation. The dissertation as a whole builds on and contributes to the literatures of gender & politics, political parties, and electoral studies. It is composed of five independent articles, of which two are published in peer-reviewed journals and an edited volume, and three are currently under review. The first article, "The adoption of youth quotas after the Arab uprisings", was published in Politics, Groups, and Identities and compares the actors and processes leading to the adoption of gender and youth quotas in Tunisia and Morocco (Belschner 2018). The second article, "Hierarchies of Representation: The Re-distributive Effects of Gender and Youth Quotas", co-authored with Marta Garcia de Paredes, is in the second round of R&R at Representation and explores the intersectional effects of paired gender and youth quotas cross-nationally and in three case-studies of Tunisia, Morocco, and Sweden. The third article, "Empowering Young Women? Gender and Youth Quotas in Tunisia", was published in Darhour and Dahlerup 2020 and investigates the backgrounds of young female MPs and their positions in the Tunisian parliament (Belschner 2020). The fourth article, "Electoral Engineering in New Democracies. Parties, Quotas, and Institutional Uncertainty" is currently under review. It focuses on Tunisian local elections and asks under what conditions parties are willing and able to comply with quotas for multiple groups. The fifth article, "Youth Advantage vs. Gender Penalty: Selecting and Electing Young Candidates" is under review as well and analyses the conditions for young candidates' electoral success in Irish local elections. Theoretically, methodically, and empirically, all articles stand on their own. To varying degrees, they all employ quantitative as well as qualitative data and while some are classical (comparative) case-studies, others take a cross-national perspective to address the above-mentioned research questions. Geographywise, the articles focus on North Africa, particularly Tunisia, and Western Europe, particularly Ireland. Tunisia is one of the few countries that has legislated yo...