Using an economic analysis of market forces in schooling, this paper investigates change and diversity in the 14-19 curriculum of 16 schools in three local education authorities in England. Using qualitative data from interviews with several teachers in each school, it focuses on changes in the schools' curriculum for modern foreign languages, economics, and business studies. During the period studied, schools had some freedom to choose the courses they offered in these subjects. The interaction between the policies of promotion of competition through comparison (i.e. league tables) and the promotion of competition through specialization is considered. Evidence is found of the influence of local schoolingmarket hierarchies on curriculum change in these schools, and this operated chiefly through changes in school enrolment. Some evidence was found of schools' curricula being influenced by trends set by key schools and the occupation of niches pre-empting choices by other schools. These processes were slowly developing and deepening as market changes exert stronger constraints on school behaviour over time. It is concluded that the impact of quasi-markets on schools' curricula may only be apparent when these processes have had the opportunity to develop more fully.