Drawing on the case of upper secondary education in Stockholm, this article analyses school-based responses to a superimposed market and how this is related to social stratification. Furthermore, schools' and pupils' encounters with the market are analysed in relation to Bourdieu's concepts of field, capital and strategy. Methodologically, the quantitative method of correspondence analysis is combined with semi-structured interviews with senior administrative officers and principals. Analysis shows how the overarching structure of this particular field -- a historically pre-existing social order of upper secondary education in Stockholm -- is related to the complex set of strategies that schools develop in the school market. Schools located at the elite pole of the field, serving the educational needs of a small minority of either the wealthy or the culturally rich upper middle class, are less affected by marketization. In the most populous social mid-tier of the field, schools are more likely to turn education into a mass-produced commodity, while schools at the socially dominated pole, without a competitive product, are more exposed to the market's stratifying impact.