We assessed factors related to smoke-free policies among a cross-sectional, nationally representative, random-digit-dial sample (landline and cell phone) of US multiunit housing residents (n = 418). Overall, 29% reported living in smoke-free buildings, while 79% reported voluntary smoke-free home rules. Among those with smoke-free home rules, 44% reported secondhand smoke incursions in their unit. Among all respondents, 56% supported smoke-free building policy implementation. These findings suggest that smoke-free building policies are needed to protect multiunit housing residents from secondhand smoke in their homes.