'Who Does What' refers to the ongoing Canadian debate about appropriate service delivery responsibilities across government levels—what services should federal, provincial, and municipal governments provide, and how should they be funded? The term gained prominence during Ontario's 1990s restructuring that downloaded services to municipalities while uploading others to the province. Who Does What debates involve efficiency arguments (which level can best deliver services), accountability considerations (connecting service decisions to funding responsibility), fiscal capacity questions (whether governments have revenue tools matching their responsibilities), and constitutional constraints. Service responsibility and funding often don't align—municipalities deliver services with costs driven by provincial or federal decisions. Periodic reviews and ongoing advocacy address Who Does What issues, though comprehensive realignment remains elusive.