This paper analyzes 50 years of inflation expectations data from multiple sources, documenting substantial disagreement among both consumers and professional economists about expected future inflation. This disagreement varies over time, moving with inflation, the absolute value of the change in inflation, and relative price variability. The authors argue that a satisfactory model of economic dynamics must account for these business cycle moments. They show that a simple "sticky-information" model broadly matches many of these facts. The sticky-information model is also consistent with other observed departures of inflation expectations from full rationality, including autocorrelated forecast errors and insufficient sensitivity to recent macroeconomic news. The paper discusses survey data on inflation expectations from three sources: the Michigan Survey of Consumer Attitudes and Behaviors, the Livingston Survey, and the Survey of Professional Forecasters. These data show that inflation expectations are relatively accurate, with forecast accuracy improving as the group making the forecast becomes more sophisticated. However, differences across groups largely reflect different periods over which each survey has been conducted. The paper also examines the dispersion of inflation expectations across different populations, finding that there is substantial disagreement within each survey, with the extent of disagreement varying over time. Disagreement among professional forecasters rises and falls with disagreement among economists and the general public. The authors find that disagreement among professional forecasters, economists, and the general population tends to exhibit similar time series patterns, albeit of different amplitude. The paper then examines the central tendency of inflation expectations, finding that median inflation expectations are relatively accurate, but do not fully incorporate recent macroeconomic information. The authors also test adaptive expectations, finding that observed inflation expectations are consistent with neither the sophistication of rational expectations nor the naivete of adaptive expectations. The paper then examines the dispersion of inflation expectations, finding that it is positively correlated with the inflation rate and the recent variance of measured inflation. The authors also find that dispersion in inflation expectations is positively correlated with the dispersion in actual inflation rates across different CPI categories. The paper then examines theories of disagreement, finding that the sticky-information model generates disagreement in expectations that is endogenous to the model and correlated with aggregate variables. The sticky-information model is shown to be consistent with the observed data on inflation expectations, including the dispersion of expectations and the central tendency of expectations. The paper concludes that the sticky-information model provides a reasonable explanation of the observed data on inflation expectations, including the dispersion of expectations and the central tendency of expectations. The authors argue that the sticky-information model is consistent with the observed data on inflation expectations, including the dispersion of expectations and the central tendency of expectations.This paper analyzes 50 years of inflation expectations data from multiple sources, documenting substantial disagreement among both consumers and professional economists about expected future inflation. This disagreement varies over time, moving with inflation, the absolute value of the change in inflation, and relative price variability. The authors argue that a satisfactory model of economic dynamics must account for these business cycle moments. They show that a simple "sticky-information" model broadly matches many of these facts. The sticky-information model is also consistent with other observed departures of inflation expectations from full rationality, including autocorrelated forecast errors and insufficient sensitivity to recent macroeconomic news. The paper discusses survey data on inflation expectations from three sources: the Michigan Survey of Consumer Attitudes and Behaviors, the Livingston Survey, and the Survey of Professional Forecasters. These data show that inflation expectations are relatively accurate, with forecast accuracy improving as the group making the forecast becomes more sophisticated. However, differences across groups largely reflect different periods over which each survey has been conducted. The paper also examines the dispersion of inflation expectations across different populations, finding that there is substantial disagreement within each survey, with the extent of disagreement varying over time. Disagreement among professional forecasters rises and falls with disagreement among economists and the general public. The authors find that disagreement among professional forecasters, economists, and the general population tends to exhibit similar time series patterns, albeit of different amplitude. The paper then examines the central tendency of inflation expectations, finding that median inflation expectations are relatively accurate, but do not fully incorporate recent macroeconomic information. The authors also test adaptive expectations, finding that observed inflation expectations are consistent with neither the sophistication of rational expectations nor the naivete of adaptive expectations. The paper then examines the dispersion of inflation expectations, finding that it is positively correlated with the inflation rate and the recent variance of measured inflation. The authors also find that dispersion in inflation expectations is positively correlated with the dispersion in actual inflation rates across different CPI categories. The paper then examines theories of disagreement, finding that the sticky-information model generates disagreement in expectations that is endogenous to the model and correlated with aggregate variables. The sticky-information model is shown to be consistent with the observed data on inflation expectations, including the dispersion of expectations and the central tendency of expectations. The paper concludes that the sticky-information model provides a reasonable explanation of the observed data on inflation expectations, including the dispersion of expectations and the central tendency of expectations. The authors argue that the sticky-information model is consistent with the observed data on inflation expectations, including the dispersion of expectations and the central tendency of expectations.