Violence and aggression on pediatric psychiatry units has led to staff and patient injuries and even deaths around the country. In an effort to improve safety, the investigators have developed a method (with the Brief Rating of Child and Adolescent Aggression) of identifying children and adolescents at a higher risk for aggression and violence on the units. In order to improve this prediction, the investigators plan to study salivary hormones in low risk children and high risk children. The salivary hormones to be studied include cortisol, testosterone, and dehydroepiandrosterone sulfate (DHEAS). The investigators expect to improve the investigators current ability to predict the severity and type of pediatric aggression and violence on the inpatient units by combining information from the Brief Rating of Child and Adolescent Aggression (BRACHA), the Predatory-Affective Aggression Scale (Vitiello et al., 1990), and salivary hormones.