A number of studies have demonstrated a clear link between impulsivity and ecstasy use (e.g. Bobes et al., 2002; Butler & Montgomery, 2004), however there is a lack of consensus to what actually constitutes impulsivity. The primary aim of the present thesis was to utilise Dawe and Loxton’s (2004) proposal for a two facet model of impulsivity, by investigating both Eysenck’s (1967) rash impulsivity and Gray’s (1987) reward sensitivity in the initiation and maintenance of ecstasy use. The present study further aimed to integrate personality theory with cognitions by investigating how impulsivity influences the motivations to use the drug. The sample comprised 220 participants, 87 males and 133 females. Of this sample 109 reported never having taken ecstasy, whereas the remaining 111 participants reported having ever consumed the drug. Participants completed a battery of assessments including measures of rash impulsivity (I7), reward sensitivity and sensitivity to punishment (SPSRQ), motivations (MDUS), and affect (PANAS). Results indicated that ecstasy use was associated with high rash impulsivity, high reward sensitivity and reduced sensitivity to punishment. Motivations for use were also associated with these impulsive personality traits, in particular negative affect mediated the relationship between rash impulsivity and the motivation to use in order to reduce negative affect. Results are discussed within the context of the two-factor model of impulsivity and the implications of these findings for intervention programs are considered.