This article documents the role of inflows (new listings) and outflows (sales) in explaining the volatility and comovement of housing-market variables. An “ins versus outs” decomposition shows that both flows are quantitatively important for housing-market volatility. The correlations between sales, prices, new listings, and time-to-sell are stable over time, whereas the signs of their correlations with houses for sale are found to be time-varying. A calibrated search-and-matching model with endogenous inflows and outflows and shocks to housing demand matches many of the stable correlations and predicts that the correlations with houses for sale depend on the source and persistence of shocks.