Community-acquired pneumonia in older adults represents an important clinical and public health challenge. This article discusses the role that factors such as socioeconomic status, air pollution, crowding, exposure to tobacco smoke, and nutrition play in predisposing elderly persons to such respiratory infections. It is proposed that a model that addresses these factors is needed for a comprehensive understanding of these infections. Although the causal pathways may be unclear, there are data to suggest a relationship between low socioeconomic status and risk of acquiring respiratory infection. The need for more research in this area is emphasized.