Our study sought to demonstrate the importance of attending to methodological issues in the study of personality characteristics of offspring of substance abusers (OSAs). A 4 x 2 factorial design, Parental Mental Health (no known psychological problems, substance abuse, other psychological problems, or dual diagnosis) x Exposure to Abuse/Neglect (present or absent), was used to examine depression proneness, neuroticism, alexithymia, self-esteem, self-concept, and locus of control in young adults. Results of this study demonstrated that in order to determine whether characteristics of OSAs are uniquely related to parental substance abuse, a psychiatric control group is needed. Also, the importance of separating the influences of other family environment variables (e.g., exposure to abuse/neglect) was demonstrated. None of the differences between groups in this study could be attributed to parental substance abuse per se; rather, the concomitants of substance abuse (i.e., exposure to abuse/neglect) were found to be more strongly related to poorer adjustment in OSAs. Finally, it was shown that the proportion of treatment-seeking subjects included in the sample affected the level of pathology observed. These results are discussed in relation to previous findings, and recommendations regarding methodology are made for future studies.