Reducing runoff sediment and nutrient loss as well as nutrient leaching from croplands is a high priority to mitigate nonpoint-source pollution (NPSP) of water sources, maintain soil fertility, and improve overall soil and water quality. Adoption of cover crops (CCs) can be a reemerging strategy to address these concerns. This article reviews the state-of-knowledge of CC impacts on water quality parameters, discusses factors that affect CC impacts, and identifies research areas.