We describe two short form versions of the self-report Aggression Questionnaire initially developed by Buss and Perry (1992). Often referred to as the Buss-Perry Aggression Questionnaire (BPAQ) the original inventory consists of 29 items that measure four aspects of trait aggressiveness – anger, hostility, verbal- and physical-aggression – that are typically used both individually and/or combined to create an overall aggressiveness index. The BPAQ is the successor of the Buss-Durkee Hostility Inventory (BDHI; Buss & Durkee, 1957). Perhaps more appropriate for Internet-based research are the AQ-12 and AQ-15 short forms derived from two different efforts to refine the BPAQ. One effort resulted in the AQ-12 (Bryant & Smith, 2001, p. 150), which uses 12 of the original 29 AQ items. The other effort yielded the AQ-15 by drawing from a 34-item AQ revision by the same authors (Buss & Warren, 2000, pp. 13, 65) and also from the AQ-12. Comparing the AQ-12 and AQ-15 reveals almost identical items for the anger, hostility, verbal- and physical-aggression subscales. The primary difference is that the AQ-15 features an additional 3-item subscale that assesses indirect aggression. Respondents typically rate items on both inventories using a Likert-type scale. Both forms can be used with adult/adolescent and normal/abnormal populations. For children, the AQ-15 may be preferable because it has a third-grade readability level. Research has shown both inventories to be quite reliable and valid measures of aggressive tendencies in individuals.