The data analyses suggest an adequate model fit, which is consistent with the proposition that positive attitudes toward consumption of alcohol and ecstasy mediate the effects of sensation-seeking for both substances. Sensation-seeking influenced consumption partially in the case of alcohol or completely in the case of ecstasy through the development of positive attitudes toward consumption. Sensation-seeking apparently strengthens the attitude-consumption relationship, possibly by leading to impulsive behavior incompatible with careful analysis of the information available on the adverse effects of ecstasy use. Study results emphasize the need to address the differential role of sensation-seeking in the use of alcohol and ecstasy (i.e., direct, moderating, or mediated by attitudes). This should result in the designing of evidence-based intervention programs for restraining each type of consumption. The study sample consisted of 450 high-school White students who ranged in age from 14 to 18. They were recruited from 8 schools randomly selected from the 28 schools located in the cities of Alcorcon and Mostoles in the Madrid Autonomous Region (Spain). Participants completed a battery of questionnaires. The sensation-seeking trait was measured with Zuckerman’s Sensation-Seeking Scale Form V. A scale was developed for assessing attitudes toward alcohol consumption and ecstasy consumption. 3 tables, 2 figures, and 58 references