In this article, I explicitly solve dynamic portfolio choice problems, up to the solution of an ordinary differential equation (ODE), when the asset returns are quadratic and the agent has a constant relative risk aversion (CRRA) coefficient. My solution includes as special cases many existing explicit solutions of dynamic portfolio choice problems. I also present three applications that are not in the literature. Application 1 is the bond portfolio selection problem when bond returns are described by ‘‘quadratic term structure models.’’ Application 2 is the stock portfolio selection problem when stock return volatility is stochastic as in Heston model. Application 3 is a bond and stock portfolio selection problem when the interest rate is stochastic and stock returns display stochastic volatility. (JEL G11) There is substantial evidence of time variation in interest rates, expected returns, and asset return volatilities. Interest rates change over time, and although expected stock returns are not directly observed, future stock returns seem to be predictable using term structure variables and scaled prices such as dividend yields. 1 Similarly, there is well-documented evidence of stochastic volatility, 2 whose existence is also supported by the ‘‘smile curve’’ of volatilities implied by option prices. Therefore, any serious study of dynamic portfolio choice must take account of stochastic variation in investment opportunities. The seminal work of Merton (1971) establishes the framework for dynamic portfolio choice with stochastic variation in investment opportunities. The portfolio weights in Merton’s framework are expressed in terms of the solution to a nonlinear partial differential equation (PDE), and because there is no closed-form solution of a nonlinear PDE in general, explicit portfolio weights are not available in general. There are approximate solutions to