This paper examines the socio-cognitive processes underlying intentions to use condoms and contraceptive pills, using the Theory of Planned Behaviour extended with prototypes in a group of young Norwegian adolescents. The data are derived from a questionnaire survey comprising all pupils in Grade Nine at three schools in Oslo (n = 196). Using hierarchical multiple regression analyses, the results showed that prototypes and normative beliefs, especially partner's opinion, were the most important predictors for boys' condom decisions. For girls' condom decisions, normative and attitudinal considerations were most important. Perceived risk of getting sexually transmitted diseases was the most important predictor among behavioural beliefs for condom intention for both girls and boys. Normative beliefs, and especially parental opinions, were most important for girls' decisions to use contraceptive pills. Implications of the findings are discussed. (Contains 3 tables.)