This study examines the effects of affirmative action bans in four states (California, Florida, Texas, and Washington) on the enrollment of underrepresented students of color within six different graduate fields of study: the natural sciences, engineering, social sciences, business, education, and humanities. Findings show that affirmative action bans have led to the greatest reductions in science-related fields of engineering, the natural sciences, and the social sciences. These declines pose serious long-term consequences for the United States since these fields provide specialized training critical to the nation's ability to compete effectively in a global market and for ensuring continued scientific and technological advancement. (Contains 5 tables, 1 figure, and 21 notes.)