Stress has been implicated in many mental and physical illnesses. Stressful events may serve to promote or exacerbate pathological states, including depressive disorders, cardiovascular disease, and immunologically related pathologies. Our work has focused on determining the conditions that increase vulnerability to stress related pathologies, including the contribution of various organismic (genetic, age) and experiential variables (stressor history, early life trauma, chronicity of events, maternal factors), and the identification of the neurochemical underpinnings for stressor-related pathology. As well, we have been assessing the processes by which the brain influences the immune system, and conversely the processes by which immune activation comes to affect brain functioning.