This study examined exposure to environmental tobacco smoke (ETS), a major public health problem. ETS has been found to be associated with an increased risk of adverse health effects in children. This study utilizes data from a community-based, longitudinal investigation examining the relation between children's exposure to ETS and later internalizing symptoms and externalizing behaviors. Interviews were administered to a representative community sample of participants from two New York State counties in 1983, with subsequent interviews in 1985-1986, 1992, 1997, and 2002-2003 (when the participants' mean age was 32). Data was collected on various personality and behavioral characteristics of the participants, and on internalizing symptoms and externalizing behaviors demonstrated by their children. Results indicated that children's exposure to ETS was associated with an increased risk for both internalizing symptoms and externalizing behaviors. This relationship was maintained despite control on a number of parental psychosocial risk factors (e.g., demographic variables, personality and behavioral attributes) that have been found to be associated with both parental cigarette smoking and behavior problems among children. These data, which indicate an association between exposure to ETS and internalizing symptoms and externalizing behaviors among children, support public health policies to further restrict children's exposure to ETS.