The aim of this study is to compare clinical (substance dependent) and nonclinical (recreational substance) populations based on substance dependence level in order to establish whether dependence levels may influence antisocial attitudes, impulsivity and aggression. Materials include the Leeds Dependence Questionnaire (LDQ), the Barratt Impulsiveness Questionnaire Version 11 (BIS-ll), the Mach IV, and the revised Anger, Irritability and Assault Questionnaire (AIAQ). There are 60 participants, 30 recreational substance users and 30 substance dependent participants. This study is a quantitative, between-subjects design, cross sectional, one time point only design, correlational design. Pv's are substance dependence, impulsivity and aggression, Cv is antisocial attitudes. For the non clinical sample random participants in Dublin City Centre were approached and asked for their involvement in the study. Of those who agreed all participants completed their questionnaires. In terms of the clinical sample, the research was conducted in Rialto Community Drug Team. Four participants withdrew from the study. Four more individuals were then included in the study. All participants then completed the questionnaires. Results indicated that substance dependant sample had higher levels of antisocial attitudes, impulsivity and aggression. Substance dependence, impulsivity and aggression in combination were predictive of antisocial attitudes. The Conclusions drawn indicate that level of substance dependence influences antisocial attitudes, and the co-occurrence of these factors, in conjunction with impulsivity and aggression may be the result of an underlying common genetic vulnerability.