Ascertaining the status of reason and rationality is one of the basic concerns of philosophy of educational. In this exposition an effort will be made to base on the Islamic teaching, investigate the situation of reason in an Islamic system of education. For this purpose, to begin with an analysis into the meaning, both lexical and topical, of the term reason (Aql) is made and the significance of reason and rationality in the Islamic literary tradition is touched upon; then, bearing the Islamic origins and domain of rationality in mind, the various dimensions of rationality are explored and explained and a number of important questions regarding reason, particularly concerning its potentials and limitations, its individual and social essence, and its relationships with sensation and emotions, on the one hand, and with particular and ethical actions, on the other, are explored. In the end, laying some emphasis on the fundamental characteristics of reason, gathered from the above -mentioned questions, a number of educational implications in areas of methodology and curriculum are drawn.