The authors define peer tutoring and describe the types of peer tutoring reported in the literature. An organizational typography of peer tutoring in school classrooms is presented, and the variables that influence patterns, nature and effectiveness of peer interaction are explored. Cognitive models of peer tutoring approaches that follow either Piagetian theories of cognitive conflict or Vygotskian theories of co-construction are compared and the similarities and differences of each model interrogated. The influences each model may have on cognitive and affective development, as well as metacognition, are illustrated. The authors discuss knowledge transfer issues to facilitate the development of effective models of peer tutoring in the classroom practice of teachers in schools. Finally, areas for future research and development are highlighted.