Drumlins remain a major problem in glacial geomorphology such that no satisfactory explanation to their mode of origin exists. This review attempts, by looking at specific subsections of the drumlin problem, to place in perspective the known facts and observations on drumlins. The most recent drumlin origin theories are examined in the light of our knowledge of the subglacial environment. Although it may seem that every aspect of this unusual landform has been researched, the author will suggest areas where new studies might begin. The interdisciplinary nature of present research into drumlins is stressed. Finally emphasis is placed on finding an explanation of drumlin formation that is not unique but one which will explain this landform's development as only one product of the complex subglacial environment.