This paper describes briefly the development and key features of one of the major context-based courses for upper high school students, Salters Advanced Chemistry. It goes on to consider the research evidence on the impact of the course, focusing on teachers' views, and, in particular, on students' affective and cognitive responses. The research evidence indicates that students respond positively to the context-based approach adopted in Salters Advanced Chemistry, and that they develop levels of understanding of chemical ideas comparable with those taking more conventional courses. Finally, issues to do with the development and evaluation of large-scale curriculum projects are considered. (Contains 2 tables.)