Background School systems are increasingly typified by diversity of provision, parental choice and publication of performance data. Schools shape their students' lifestyles and health, but the effects of ‘marketisation’ are under-researched. The authors use qualitative data to develop a logic model regarding such effects.

Methods Case studies in seven English secondary schools, interviews with 103 students and 39 staff.

Results ‘Parental choice’ was associated with dispersal of students' friendship groups on transition to secondary school, reduced social support and emotional harms. ‘Choice’ meant some schools were regarded as ‘dumping grounds’ for socially disadvantaged students, creating potentially violent environments where students engaged in risk behaviours such as substance use to facilitate protective bonds with peers. Schools focused strongly on academic attainment, reflecting external pressures from the school inspectorate and performance league tables. Some schools sought to improve their league table position by targeting resources on ‘key marginal’ students on the threshold of passing five exams, the key metric. Less-academic students commonly became disengaged, engaging in various health risk behaviours as alternative status markers. The exam-focused environment aroused anxiety among high and low attainers, some using substances as self-medication. Schools also de-prioritised health education and sport in this performance-driven context.

Conclusion Our logic model aims to guide further research on how marketisation might affect young people health behaviours.