We conducted a qualitative interview study with people of different professions working with lonely elderly people. The rationale of the study was to examine how these respondents explain loneliness among the elderly. The present article focuses on the social explanations, i.e. explanations that identify causes of loneliness in the structure of modern society. We found that many of the social explanations given are aspects of a more encompassing and general pattern underlying all the reasoning about loneliness among the elderly. This pattern is the expression of two contrasting images of society which the classical sociologist Ferdinand Tönnies termed Gemeinschaft (community) and Gesellschaft (society). The former refers to traditional or small-size rural communities characterized by high degrees of social cohesion, integration, solidarity, proximity and familiarity, whereas the latter refers to functional differentiation, distance, individualization, exchanged-based social relations and anonymity. Loneliness among the elderly is explained by the lack of Gemeinschaft and its characteristics in contemporary society. This explanatory pattern goes hand in hand with a critical view of contemporary society and a nostalgic yearning for the lost communities of past societies, where inhabitants find their staked-out place and sense of belonging, and thus loneliness hardly seems to occur. We summarized this view under the label the "lost Gemeinschaft".