Should a policy rule include money? Including money exerts policy inertia and increases inflation aversion. In a New-Keynesian model with trend inflation, these features guarantee price determinacy even when the Taylor principle is not satisfied. Novel Greenbook data confirm money aggregates as U.S. Federal Open Market Committee policy objectives, enabling monetary policy to insulate the U.S. economy from self-fulfilling fluctuations despite positive trend inflation. A high response to inflation and low trend inflation guarantees determinacy post-1982. Cross-country applications highlight the superiority of the rule with money. Raising the inflation target from 2 percent to 4 percent violates the Taylor principle; including money resolves this issue.