"This paper studies strategic asset allocation and consumption choice in the presence of regime switching in asset returns. We find evidence that four separate regimes - characterized as crash, slow growth, bull and recovery states - are required to capture the joint distribution of stock and bond returns. Optimal asset allocations vary considerably across these states - both among bonds and stocks and among large and small stocks - and change over time as investors revise their estimates of the underlying state probabilities. In the crash state investors always allocate more of their portfolio to stocks the longer their investment horizon, while the optimal allocation to stocks declines as a function of the investment horizon in bull markets. The joint effects of learning about the underlying state probabilities and predictability of asset returns from the dividend yield give rise to a non-monotonic relationship between the investment horizon and the demand for stocks. Consumption-to-wealth ratios are found to depend on the underlying state and welfare costs from ignoring regime switching are substantial even after accounting for parameter uncertainty. Out-of- sample forecasting experiments confirm the economic importance of accounting for the presence of regimes in asset returns"--Federal Reserve Bank of St. Louis web site.