This article examines the legal and moral basis of affirmative action in science and engineering, in light of recent legal rulings by the U.S. Supreme Court. It argues that affirmative action programs can be morally and legally justified on the grounds that they enhance educational experiences and promote creativity, productivity, and success in science and engineering. Affirmative action programs may use race, ethnicity, or gender as one factor among many in decision-making, but they should not treat race, ethnicity, or gender as a decisive factor. Affirmative action programs that establish racial, ethnic or gender quotas are not legally or morally justifiable.