The four principal U.S. oilseed crops are soybeans, cottonseed, peanuts, and sunflower seed. The physical characteristics of the plants and seeds, chemical compositions of the seeds, harvesting and storage of the crops, and processing of the crops into oil and defatted meal are described for the primary products of the industry. Production figures and prices of the oilseeds and their products are presented. The oils of these crops are used primarily for human consumption. Minor quantities go into industrial products. The defatted meals serve mainly as protein sources in animal feeds, but small amounts are processed into protein ingredients used by the food industry. Nutritional properties and antinutritional factors of the oils and meals are reviewed. Direct food uses of soybeans, peanuts, and sunflower seed are also covered.