Objective: The relationship of parental alcohol or drug diagnosis to offspring personality was examined in a population-based sample of 17-year-old twins (568 girls and 479 boys) participating in the Minnesota Twin Family Study. Whether offspring personality characteristics 1) are specific to the type of substance use disorder in parents (alcohol versus drug) and 2) are found in high-risk offspring without substance use disorders as well as in offspring with substance use disorders was investigated. Method: Personality was assessed with the Multidimensional Personality Questionnaire; substance use disorders were assessed in person through diagnostic interviews. Results: In both male and female offspring, parental history of alcohol dependence was associated with greater negative emotionality, aggression, stress reaction, and alienation but lower well-being; parental history of drug disorders was associated with lower constraint, control, harm avoidance, and traditionalism but higher social potency. Excluding offspring with a substance use disorder had virtually no effect on the statistical significance of these findings. Conclusions: In contrast to findings in some adult samples, personality characteristics associated with a family history of substance use disorders are found even in adolescent offspring who have not yet developed these disorders themselves, suggesting that personality might be one indicator of familial risk for substance use disorders during this developmental stage. Personality profiles of offspring of parents with substance use disorders also show some diagnostic specificity, with constraint associated with parental drug abuse and negative emotionality with parental alcoholism.