Young people are under-represented in most political institutions, from local assemblies and mayoral offices to national legislatures. While studies have long shown that characteristics such as race, gender, class, and sexual orientation influence politicians' choices in office, however, we lack research on whether the age bias of institutions has similar consequences for policy outcomes. Understanding whether a policymaker's age affects their decision-making is especially important in rapidly aging societies such as Japan, where politicians confront soaring social welfare costs and tough decisions about allocating resources between efforts to encourage younger people to have more children and support a growing elderly population. Without the presence of more young people in public office, there is a concern that the decisions made by mostly older politicians will lead to welfare policies that favor the elderly at the expense of younger families. Older politicians may also be less willing than younger politicians to address long-term issues such as social welfare reform, which will have a greater impact on younger generations.

This dissertation is about the causes and consequences of youth under-representation in democracies. I examine the institutional factors that help explain the variation in the age of politicians across elected offices, and whether voters have preferences concerning their representatives' ages. I also analyze whether the age of politicians affects the welfare policies they pursue in office. To do so, I draw on months of fieldwork in Japan and an original, candidate-level dataset of Japanese mayoral and municipal assembly elections over the past twenty years (1999-2019). Through chapters that utilize text analysis, regression discontinuity designs, and survey experiments, I provide evidence that age influences elected officials' behavior along two key dimensions. First, age affects elite preferences for the redistribution of welfare between age groups: younger politicians promote and implement policies that benefit younger families more than older politicians. Second, I find that the age of representatives shapes how they allocate welfare resources over time: younger politicians with longer time horizons are more willing to make long-term investments in child welfare infrastructure, whereas older politicians are more likely to increase short-term benefits for the elderly.