About half of U.S. farm workers are not authorized to work in the United States. Pending immigration reforms aim to prevent the entry and employment of more unauthorized foreigners, but they differ on what to do about unauthorized workers already in the United States. These unauthorized workers are not likely to disappear overnight, and agricultural adjustments to a legal work force are likely to be determined by enforcement patterns, the structure of new guest worker programs, and the speed at which current farm workers find nonfarm jobs.