Purpose: Caregivers feeling stress and experiencing mental health problems can be at risk for engaging in abusive acts against elderly care recipients. Potentially harmful behavior (PHB) was used as a measure of caregivers' engagement in, or fear of engagement in, behavior that places dependent care recipients at risk of physical and/or psychological maltreatment and may be seen as an antecedent of, or a proxy for, identifiably abusive behavior. The study examined the ability of anger to mediate and moderate the relations of depression, resentment, and anxiety with PBH. Design and Methods: Data are from the first wave of the second Family Relationships in Late Life study of caregivers of community-dwelling elderly care recipients with whom they coreside. Caregivers (N = 417) completed face-to-face interviews. Results: Anger was found to mediate the relation between anxiety and PHB. Anger both mediates and moderates the relations of both depression and resentment with PHB in a dynamic way such that the mediating effect of anger increases substantially with increased scores on both depression and resentment. Implications: Identifying anger levels among caregivers who report symptoms of depression is warranted. Reducing depression in caregivers who report high levels of anger may result in reductions of PHB. Screening for resentment is warranted, as the relation between resentment and anger is similar to that between depression and anger.