Early intervention in mental disorders can dramatically increase an individual's quality of life. Additionally, when symptoms of mental illness appear in childhood or adolescence, they represent the later stages of a process that began years earlier. One goal of psychiatric research is to identify risk-markers: genetic, neural, behavioral and/or social deviations that indicate elevated risk of a particular mental disorder. Ideally, screening of risk-markers should occur in a community setting, and not a clinical setting which may be time-consuming and resource-intensive. Given this situation, a system for automatically detecting risk-markers in children would be highly valuable. In this paper, we describe such a system that has been installed at the Shirley G. Moore Lab School, a research pre-school at the University of Minnesota. This system consists of multiple RGB+D sensors and is able to detect children and adults in the classroom, tracking them as they move around the room. We use the tracking results to extract high-level information about the behavior and social interaction of children, that can then be used to screen for early signs of mental disorders.