The Saqqaq Culture site Qeqertasussuk (2400-1400 BC) is situated in the south eastern corner of Disko Bay, West Greenland. The site was excavated between 1983 and 1987 by Qasigiannguit Museum. The stratified cultural deposits are exceptionally well preserved by permafrost and yielded hundreds of thousands of animal bones, feathers, plant remains, insect remains, wooden implements, and a wealth of other organic refuse as well as stone tools, house ruins, stone set fireplaces and other traces of habitation. In order to understand the life conditions of the inhabitants at Qeqertasussuk, a comparative survey of the historic distribution, density and availability of the living resources in the area is undertaken. This resource model is then evaluated against the paleo-environmental data. Also, comparative ethnohistorical and ethnographic data on the exploitation of the living resources in the area is presented. Subsistence and subsistence change at Qeqertasussuk is studied through a comprehensive analysis of the faunal material that consists of more than 200,000 animal bones. Quantitative methods are supplemented by detailed studies of seasonality and age composition of the hunting bag. Forty three species of animals are represented. Harp seal and ringed seal represent the most important game, but sea birds such as fulmar, Brünnich's guillemot, and little auk also play a significant role in the subsistence economy. Fish, especially Atlantic Cod, have been caught and remains of large whales indicate that these animals were utilized, but it can not be decided whether they were actively hunted. Most of the game was taken close by the site, however finds of caribou indicate that inland caribou hunting was undertaken and that Qeqertasussuk was part of a larger subsistence-settlement-system. Several species of plants were also utilized. Temporal changes in the composition of the faunal material indicate that significant changes occur in the subsistence at Qeqertasusuk. Four phases are identified: (1) Basecamp period I (2400-2100 BC). A pioneer phase where the site is used as a year-round base camp with more than 90% of the biomass being harvested within an area of approximately 80 km2, (2) Base-camp period II (2100-1900 BC), which seems to be the period of most intensive use and where new methods (probably netting) of harp seal hunting are introduced, (3) Hunting camp period (1900-1700 BC), where the site becomes more specialized and more seasonal with a focus on spring-summer hunting for harp seals, (4) high activity period (1700-1400 BC) indications of continued heavy sea mammal hunting. The site was abandoned around 1400 BC. The causes of the abandonment of Qeqertasussuk is discussed and the impact of the general cooling around 1500 BC on key resources such as harp seal and capelin is highlighted.