The Polar Eskimo, who inhabit the northwest portion of Greenland con-tiguous to the waters of Smith Sound, are the northernmost people in the world. Along eight hundred miles of desolate shore, from Cape Seddon in latitude 76 to the Humboldt Glacier in latitude 790 north, they have persisted for centuries as a unique little social group of about two hundred and fifty individuals, quite successful in their hard struggle for existence by an almost perfect adaptation to the rigorous conditions of their far northern homeland. Their number, determined by the years of minimum food supply, has probably never been much greater or much smaller than now. Their homeland, though extensive, is small in area because the Greenland ice-cap, which covers practically all the high plateau of Greenland, restricts all life to a narrow belt along the shore, free of ice and snow during the short summer. Their climate, though Arctic, is essentially oceanic. The periods of continuous day and continuous night are longer than those with any other people. So simple and so direct is the relationship between the Polar Eskimo and their environment that it offers a most definite and interesting study in the adaptation of the human animal to the circumstances of his habitat. The causal sequence of modifying and determining influences is not difficult to trace, and the resultant social and economic organization is not confusing or intricate. But this clear, direct relationship is fast becoming obscured by the introduction of external factors; and consequent upon a closer and more continuous contact with foreign peoples, the group is fast changing its character and culture. In another decade or two the demoralization of the Polar Eskimo as a distinct, quite independent group, will have been accomplished. This paper is an attempt to present concisely and clearly this originally simple and direct response of the Polar Eskimo to their environment, and to point out the -significant and determining factors in their habitat.