In this study, the Theory of Planned Behaviour (TPB) was used to examine the underlying factors that have an impact on high-school students’, 16-20 years old, intentions to drink so much alcohol during a forthcoming week-end that they at least get slightly drunk. The study was carried out in the form of a 46 item survey with questions based on Ajzen’s TPB-model, as well as background questions, among pupils at two senior high schools in Sweden. To check the behaviour the pupils were also asked one week later if they did actually drink any alcohol during the past week-end. The subjective norm did not work alone but when combined with descriptive norm good norm components could be formed. The result shows that the TPB-model works on the whole with attitude and norms as best predictors for intentions (R2=0,436; F=22,069; p<.001) and with attitude, norms and percieved behavioural control as predictors for behaviour (R2=0,198; F=9,454; p<.001). Intentions alone were also able to predict the behaviour (R2=0,453; F=96,729; p< .001).