Stress is an unavoidable aspect of the human experience. When the brain interprets a situation as stressful, it triggers the release of a hormone called cortisol that acts as a catalyst of the body's "fight or flight" response system. In small amounts this hormone can provide the body with the necessary tools to escape a stressful situation. However, extended periods of cortisol release may cause a host of adverse effects in the body including altering brain chemistry and function, and lowering resistance to disease. But what happens to children who endure severe, chronic childhood stressors including (but not limited to) maltreatment, specific traumas, poverty, and living with depressed parents? This article examines research assaying the levels of cortisol found in the saliva of children. The findings from these studies support the hypothesis that children experiencing severe levels of stress produce higher amounts of cortisol. There is also evidence that children with disruptive and conduct disorders also produce higher cortisol levels, likely in response to real or perceived stressors. It is important to identify the consequences of prolonged, elevated cortisol activation to better prepare schools to meet the needs of the children who are enduring stress, perceived or real threats, and/or abuse.