While rotation strategies are important in determining agricultural commodity supply and environmental benefits from land use, little has been said about the economics of crop rotation. An issue when seeking to identify rotation dominance is whether yield and input-saving carry-over effects persist for one or more years. Focusing on length of carry-over, expected profit maximization, and the monoculture decision, this paper develops principles concerning choice of rotation structure. For some rules that we develop, rotations may be discarded without reference to price levels while other rules require price data. We also show how risk aversion in the presence of price uncertainty can alter preferences over rotations. A further consideration in rotation choice is the allocation of time. The problem of crop choice to manage time commitments through the crop year is formally similar to that of crop choice to manage profit risk.