Little is known about adolescents’ own beliefs regarding their level of risk taking or regarding peer influence on the latter. This is an important matter given that beliefs influence judgements and decisions. With the present study, we aimed to study adolescents’ and adults’ beliefs about adolescents’ risk taking compared to adults’ risk taking, and beliefs about peer influence on risk taking. To this end, an experimental design was used. A cross-sectional study included 56 adolescents and 43 adults, who completed a questionnaire asking about adolescents’ and adults’ risk-taking propensity and a syllogistic reasoning task designed to indirectly study these beliefs. Both direct and indirect measures indicated that adolescents perceived adolescence as a period of higher risk taking compared to adulthood, and believed peer presence to promote this effect. Adults perceived this detrimental effect of peers to be present irrespective of age. We discuss the implications of these results in terms of social representation.