This paper examines from a Social Realist perspective a set of issues in the sociology of education regarding the problem of knowledge. It focuses upon the issue of relativism associated with the constructionist approach that since the time of the New Sociology of Education in the 1970s has constituted in different forms the dominant perspective in the field. It identifies features shared between constructionism and the "positivist" approach with which it contrasts itself. It is argued that these two positions have more in common than is often recognized and draws upon Critical Realism as an alternative to both. Social Realism explores the sociological implications of Critical Realism for education. (Contains 8 notes.)