Forty-one high-school students evaluated each of 30 activities (e.g. smoking, drinking, drug use, sex) on each of 14 characteristics of perceived risk and perceived benefit. They also indicated whether they themselves engaged in the activities. Adolescents who participated in an activity perceived the risks to be smaller, better known, and more controllable than did non-participants. Participants also perceived greater benefits relative to risks, greater peer pressure to engage in the activity, and a higher rate of participation by others. Implications for theory, research, and for health education and intervention programs are discussed.