One hundred and eighteen inpatient adolescents in a psychiatric hospital were evaluated to determine the relationship of aggression, self injury, and suicidal behavior to impulsivity. It was hypothesized that all these variables would be significantly and positively correlated with one another. This hypothesis was in part based on the results of psychobiological research that found serotonin dysfunction to be the common denominator of these psychopathological dimensions. As predicted, a significant correlation was found between the measures of suicidal behavior, aggressive behavior, and impulsivity. This correlation between suicidal behavior and impulsivity remained after partialing out the factor of aggression. Furthermore, the correlations between impulsivity and suicidality appeared greater in males than in females. Since male suicide attempters are more likely to eventually commit suicide than female suicide attempters, these findings may have a bearing on suicide prediction.