The decision to continue with science in school has a critical impact on the supply of the scientific skills necessary for a prosperous modern society. Low participation rates in post-compulsory school science have been a persistent problem and the decision process employed by students in choosing science is poorly understood. In this study, 10 focus groups were conducted with 50 students from four schools. Students were asked how they selected their subjects and their opinions on choosing science. Students described their subject selection as a two-stage process. First, they chose and rejected subjects based on enjoyment, interest and need. Second, they sought information and advice to fulfil their subject quota. Compared to other subjects, the sciences were considered more difficult and useful only for stereotypical scientific careers. It is suggested that science may be 'overpriced' and 'undervalued' by students and that these perceptions can be addressed at subject-selection time.