Aggressive behavior is not uniform, including proactive and reactive forms of aggression. Aberrant functioning of the hypothalamic–pituitary–adrenal (HPA) axis is frequently associated with abnormal aggression. Here, we review the rodent literature in order to assess whether developmental abnormalities in the HPA axis can be causally linked with the emergence of abnormal aggression. We examine studies that involve genetic models and life challenges (e.g., early life stress, drug exposure) that course with developmental alterations in the HPA axis. Although the lack of systematic studies hinders development of an integrated model, existing evidence supports a U-shaped function regarding differences in HPA axis functioning during development and the emergence of aggressive phenotypes. Thus, developmentally low or high HPA axis reactivity are typically found to be aligned with the emergence of aggressive phenotypes; however, existing information is insufficient to causally link divergent HPA axis aberration with specific types of aggression. Progress in this field is needed to support interventions in children aimed at ameliorating social dysfunctions associated with aberrations in HPA axis function.