The Life History of Aggression (LHA) is a frequently used scale for assessing trait aggression, but its psychometric properties have not been evaluated among adolescents. The aim of this study was to evaluate the psychometric properties of the LHA among high school students from Morocco, Serbia, Sweden, Vietnam, and the United States of America (USA). The total sample included 4867 adolescents, aged 15-19 years, from Morocco (n = 508), Serbia (n = 1067), Sweden (n = 1570), Vietnam (n = 1401), and the USA (n = 321). A two-factor, nine-item model containing an aggression factor (5 items) and a consequences/antisocial behavior factor (4 items) was created. The two-factor model had an acceptable-to-good model fit for the data for the total sample and all five countries, including gender. Cronbach's alpha (α) was satisfactory across countries. Still, the construct was noninvariant across countries and genders. The LHA with nine items in two subscales showed sound construct validity and internal consistency and can be used for group-level or within-group assessments of trait aggression in adolescents by either gender or country. However, it should not be used for cross-gender or cross-country comparisons due to a lack of measurement invariance.