The term illiteracy refers to a multilateral and constantly evolving issue that continues to take on alarming dimensions in the present day. During each modern historical period the factors responsible for its emergence and maintenance have been diverse and have had no national peculiarities. Illiteracy today presents itself as a particularly persistent problem in Greece, which has consistently concerned international organisations during the last five decades. The present study initially adopts a historical perspective, since it observes, records and diachronically interprets the problem of illiteracy in Greece, while also incorporating a comparative dimension, attempting to approach the issue as it has presented during various historical periods in Greece by making brief examinations of other societies. Finally, the study makes a reference to certain measures taken both through the Greek educational system and by other adult education organisations to confront this problem.