39 Arnaldo Zelli is a full professor of Psychology in the Dept. of Education Sciences in Sport and Physical Activity, University of Rome “Foro Italico.” Fabio Lucidi and Luca Mallia are with the Department of Psychology at the University of Rome-Sapienza. Journal of Clinical Sport Psychology, 2010, 4, 39-52 © 2010 Human Kinetics, Inc. The Relationships Among Adolescents’ Drive for Muscularity, Drive for Thinness, Doping Attitudes, and Doping Intentions Arnaldo Zelli University of Rome-Foro Italico Fabio Lucidi and Luca Mallia University of Rome-Sapienza This study examined the relative ways in which muscularity and thinness concerns longitudinally infuence adolescents’ intentions to use doping substances. It was hypothesized that muscularity and thinness exert their effects on doping inten- tions by promoting endorsement of positive attitudes toward doping use in male and female adolescents and across different levels of sport involvement. To test this hypothesis, nearly 900 high school adolescents provided questionnaire data on two separate occasions during an academic year. On average, boys, as well as boys and girls who practice some sport, had relatively strong concerns about muscularity, whereas girls showed relatively strong thinness concerns. Boys also expressed more positive attitudes about doping than did girls. Structural equation modeling showed that muscularity and thinness have direct effects on adolescents’ intentions to engage in doping and that muscularity, but not thinness, partly exerts its effects through the endorsement of positive attitudes toward doping. Keywords: body image, muscularity, slimness In the popular media, doping use is typically viewed as a phenomenon that involves professional athletes and that represents the primary illicit means to enhance sport performance. This public view is in sharp contrast with the ways doping use has been investigated and conceptualized in the scientifc psychologi- cal literature. First, research has demonstrated that doping use goes well beyond the realm of elite or professional sports. It is also found, albeit in relatively low percentages, among middle school and high school boys and girls who practice sports on an amateur level, with little variation in doping use across geographic regions, socioeconomic stata, and educational levels (Yesalis & Bahrke, 2000). Second, even though athletic performance enhancement represents a key goal of doping users, many athletes use doping to improve their physical appearance and