This research examined adolescent anger in a cohort of adolescents measured twice, once during the freshman year and again in the senior year of high school. Anger was measured by the Anger Index, a questionnaire developed by Siegel (1984). The purpose of the research was to determine if adolescent anger changed over time and if there were gender differences. Results of the study indicated that anger scores appeared to be stable over time for both boys and girls. There were gender and time differences on individual responses for several items, indicating that certain dimensions of anger may differ over time and by gender. It also appeared possible that the interpretation of certain questions on the anger index was different for the adolescents at the two time intervals.