James S. Coleman, among the most eminent and influential twentieth-century sociologists, sought to understand and improve the performance of social systems. A prolific contributor to both basic and applied empirical research, social science methodology, and social theory, his Introduction to Mathematical Sociology (1964) established an intellectual agenda for mathematical sociology. His 1966 study of inequality in educational opportunity had a major impact on US educational policy and much subsequent social science policy research. His Foundations of Social Theory (1990) outlined an approach to understanding social phenomena based on interdependent purposive actions. He viewed large organizations (“corporate actors”) as contemporary society's most distinctive feature, arguing that social science should help to develop new forms of social organization that are more attentive to the interests and welfare of natural persons.