Agricultural sustainability requires that the individual farm firm be competitive and profitable while simultaneously enhancing environmental quality and the natural resource base upon which the farm firm and agricultural economy depends. The reliance of conventional agriculture systems on purchased inputs external to the firm presents possible challenges to the long-term sustainability of the system. Crop rotation systems are one cropping system alternative that can reduce agriculture's dependence on external inputs through internal nutrient recycling, maintenance of the long-term productivity of the land, and breaking weed and disease cycles. Decision criteria to choose among competing crop rotation systems can include impact on soil quality and fertility, environmental quality, and farm profitability. However, most of the comparative economic analysis work reviewed for this paper considered only farm profitability as a criterion to rank alternative crop rotation systems. Most rotation research is focused around a target crop that is the foundation for the crop rotation system. When corn is the target crop, comparative profitability performance of continuous corn vs. corn grown in rotation showed that neither system is consistently more profitable than another. Corn yield in Michigan does respond favorably to crop diversity. Wheat as the target crop in rotation tends to outperform continuous wheat both in terms of profitability and income risk. Sugar beet prices hold the key in determining the profitability ranking of alternative sugar beet-based crop rotations. Potato in rotations tends to outperform continuous potato both in terms of yield and profitability. Future studies addressing the economic performance of crop rotations need to consider the environmental benefits/costs both on and off the farm site that accrue to society. Keywords: Agricultural sustainability, external inputs, soil quality and fertility, environmental quality, crop rotations, comparative economic analysis, farm profitability.