What is the output gap and when do we know it? A factor stochastic volatility model estimates the common component to forecasts of the output gap produced by the staff of the Federal Reserve, its time-varying volatility, and time-varying, horizon-specific forecast uncertainty. The common factor to these forecasts is highly procyclical and unexpected increases to the common factor are associated with persistent responses in other key macroeconomic variables. The estimates of this common factor, however, are very uncertain, even well after the fact. Output gap uncertainty increases at business cycle turning points. Lastly, increased macroeconomic uncertainty, as measured by the output gap's time-varying volatility, produces pronounced negative responses to other macroeconomic variables.