In the last 20 years, research on implicit social cognition has established that social judgments and behavior are guided by attitudes and stereotypes of which the actor may lack awareness. Research using the methods of implicit social cognition has produced the concept of implicit bias, which has generated wide attention not only in social, clinical, and developmental psychology, but also in disciplines outside of psychology, including business, law, criminal justice, medicine, education, and political science. Although this rapidly growing body of research offers prospects of useful societal applications, the theory needed to confidently guide those applications remains insufficiently developed. This article describes the methods that have been developed, the findings that have been obtained, and the theoretical questions that remain to be answered.