Despite their formal dissimilarity, problem behaviors (e.g., substance misuse, binge eating, self-harm) may share a common function. According to Acceptance and Commitment Therapy (ACT), this shared function is "Experiential Avoidance," the process of avoiding, escaping or otherwise altering unwanted private events (e.g., thoughts, feelings, memories) and the contexts that elicit them. Structural Equation Modeling was used cross-sectionally with data from a clinical opportunity sample (N = 290) to test (a) whether problem behavior covariance was associated with experiential avoidance, and (b) whether experiential avoidance mediated the relationships between historical and dispositional risk factors (childhood trauma and negative affect intensity, respectively) and the tendency to engage in problem behaviors. Analysis showed that experiential avoidance contributed to the covariation of problem behaviors, and that it fully mediated the relationships between both risk factors and problem behavior. Thus, experiential avoidance may be a key process to target in the management of individuals with behavior problems. (Contains 1 table and 2 figures.)