Professional forecasters’ long-run inflation expectations overreact to news and exhibit persistent, predictable forecast errors. We develop an imperfect-information model in which forecasters infer long-run inflation from observed inflation and forward-looking public and private information. Using individual forecasts from the U.S. Survey of Professional Forecasters, we identify two departures from rationality required by the data - overconfidence in private information, which explains overreaction, and persistent expectations bias, which accounts for the persistent, predictable forecast errors. We also uncover substantial, time-varying heterogeneity in forecasters’ responses to public information, with sensitivity declining across all forecasters when monetary policy is constrained by the effective lower bound. The model provides a real-time framework for assessing whether policymakers’ communicated inflation paths are consistent with long-run expectations remaining anchored at the central bank’s target.