This chapter addresses the growing academic and institutional interest in youth political representation, situating it as a critical issue for the legitimacy and functioning of representative democracies. Despite making up a significant proportion of the population in many countries, young people remain severely underrepresented in formal political institutions. Drawing on existing research and global data, the chapter conceptualizes youth as both a socially constructed and politically marginalized group. It reviews competing definitions of youth and political representation, exploring the implications of context-specific age thresholds and the challenges of operationalizing both descriptive and substantive representation. The chapter highlights the distinctiveness of youth as a group—transitory, heterogeneous, and shaped by demographic and cultural context—and argues that age, like gender or ethnicity, warrants targeted analytical and normative attention. The chapter normatively justifies the need for increased descriptive representation of youth and outlines how their marginalization extends beyond electoral politics into systemic power imbalances. Finally, it maps the field of youth political representation, identifies gaps, and introduces the volume’s contributions, which combine case studies and practitioner insights to expand the empirical and theoretical understanding of youth political representation.