Excavations at Margaret Bay (UNL-48), a large, multicomponent archaeological site on Amaknak Island in the eastern Aleutians, have revealed clear signs of Arctic Small Tool tradition (ASTt) elements at approximately 3300 14C years BP. At that time Neoglacial conditions brought seasonal pack ice to the eastern Aleutians as well as many of the same marine mammals hunted earlier by ASTt peoples farther north. The ASTt’s highly adaptable subsistence technology worked well in the eastern Aleutians where the rich Neoglacial environment provided the basis for relatively permanent settlement and population growth. Accumulating evidence points to an expansion of eastern Aleutian populations during the Neoglacial, and significant contacts with arctic peoples across vast distances of the American Arctic. Rather than an isolated archipelago, the Aleutians were a corridor for a surprisingly free flow of people, ideas, and materials.