Supply-side policies can play a role in fighting a low aggregate demand that traps an economy at the zero lower bound (ZLB) of nominal interest rates. Reductions in mark-ups or future increases in productivity triggered by supply-side policies generate a wealth effect that pulls current consumption and output up. Since the economy is at the ZLB, increases in interest rates do not undo this wealth effect. The paper illustrates this mechanism with a New Keynesian model.