How do inflation expectations affect stock returns, and what accounts for this relationship? We directly measure investors' expectations using traded inflation-indexed contracts and show that, post-2000, stocks offer positive returns in response to higher expected inflation: unconditionally, a 10 basis point increase in 10-year breakeven inflation is associated with a 1.1% increase in the value-weighted stock index. Using a wide range of approaches, we show that this positive relationship is almost entirely due to aggregate variations in expected excess returns rather than changes in firm cash flows (e.g., due to higher mark-ups) or fluctuations in risk-free rates (e.g., due to expected monetary policy response). Overall, a risk premium “proxy'” mechanism appears to explain this dominant role of expected excess returns: higher long-term inflation expectations signal stronger future economic growth and reduced volatility.