This paper provides the first comprehensive evidence on the multifaceted legacy of military conscription across the world. We construct a new global database of conscription policy reforms linked to hundreds of census and survey data sources. Exploiting cohort-based eligibility cutoffs, we compare individuals just eligible for service to those just exempt. On average, conscription increases men's adult socioeconomic status, driven by higher university attainment, greater geographic mobility, and the transferability of military-acquired skills. Effects are largest where the opportunity cost of service is low and reintegration into civilian life is strong. Economic gains extend to households: women who marry conscription-eligible men experience higher living standards, and their children exhibit lower mortality, despite no direct effects on women's own education or employment. Conscription also fosters interethnic marriage, national-language use, and patriotic attachment, but simultaneously increases xenophobia and gender conservatism, revealing a tradeoff between national integration and tolerance. Effects vary widely across countries depending on political institutions, development, diversity, and conscription design. Economic and sociopolitical effects are positively correlated, suggesting that nation-building is strongest where conscription delivers greater economic returns.