Long central to state-building and national integration, compulsory military service is again in focus amid rising geopolitical tensions, reviving questions about its broader consequences. We construct a novel global database of conscription reforms, linked to harmonized census and survey microdata spanning six decades. Comparing adjacent birth cohorts just drafted versus just exempt, we find that conscription increases men’s educational attainment, asset ownership, occupational status, and geographic mobility. Skill acquisition during service plays an important role in shaping these gains. Men’s economic returns, in turn, extend to women and children through the marriage market. Nation-building effects are heterogeneous: drafts introduced at independence or in diverse societies foster patriotism and interethnic integration, while other settings see increased anti-immigrant sentiment. Economic and political benefits are positively correlated but vary systematically with modernization paths and labor-market frictions. Our findings reopen the debate on whether conscription can serve as a tool for inclusive development.