Research has consistently studied environmental and biological risk factors for violence. However, recent studies have begun to examine the contribution of both biological and environmental predispositions to aggressive behavior. While there is a growing body of research examining biosocial influences, there has been a distinct lack of comprehensive research exploring the influence of parent-child interaction factors on the relationship between autonomic arousal and aggression. The current study addressed this issue by examining inconsistent discipline and parental involvement as moderators in the relationship between autonomic arousal (specifically sympathetic versus parasympathetic arousal at rest and during a task) and reactive versus proactive aggression. Data were collected from a sample of fourth graders identified as at-risk for aggression (N= 360). Inconsistent discipline was found to be a significant moderator in ten of the sixteen tested models and either gender or race acted as an additional moderator in seven of these models. Parental involvement was not a significant moderator in any of the tested models. Results demonstrated that children exhibiting both proactive and reactive aggressive behaviors may demonstrate heighted or diminished autonomic arousal patterns, but level of arousal depends on contextual and demographic factors (specifically gender, race, and the level of inconsistent discipline). By examining the influence of environmental factors on the relationship between autonomic arousal and different types of aggression, we may be better able to understand under which circumstances children with reactive versus proactive aggression exhibit heightened or reduced arousal patterns.