In order to develop a sustainable society, tools are needed to analyze the relationships between human activities and ecosystems and to estimate the carrying capacity of the natural resource base. In this paper, energy analysis is applied in a study of the small island society Nämdö in the Stockholm archipelago, Sweden. Nämdö has a permanent population of 41 persons and ca. 1000 summer residents. We estimated the energy and material flows on the island, including the primary and secondary production in natural and cultivated ecosystems, human production and consumption of food, and production of waste. Our results show that the island society's consumption exceeds the natural carrying capacity of the island. A great deal of food and energy is imported while only a minor amount of local resources are utilized. The island society is, at present, not constrained by the local resource base, but instead depends heavily on functioning transport communications with the mainland. Based on our findings we make recommendations for greater self-sufficiency, including use of locally available renewable resources and increased recycling.