Postcompulsory education is an emerging phase of educational practice. Within the turmoil of the development of new institutional arrangements, little consideration of the normative aspects of the relationship between teachers and students has been undertaken. In order to provide some guide for institutional practice, this paper considers the form of authority which might be appropriate to the rights, responsibilities and freedoms of the students and teachers within this phase of education. Broadly, the discussion centres on the distinguishing features of the concept of authority, drawn from an examination of the relationship between the concepts of authority, power, reasons, identity and freedom, and draws implications that these features have for educational practice. Rawls' theory of justice is adopted as an appropriate framework from which to examine the professional and institutional authority relationships between teachers and postcompulsory students. Implications are drawn for institutional practices together with specific recommendations for a changed professional relationship in the light of the recognition of the changed levels of responsibility and freedom of postcompulsory students.