The key role Swedish upper secondary education plays in differentiating between higher education and labour market sectors has been discussed from an equality perspective over the last 60 years. Despite political incentives to reduce social biases students’ programme choices, research shows a persistent impact of both home environment and gender. This thesis is part of a long tradition of policy informing, large-scale, recruitment research. It contributes to this tradition by viewing student recruitment in the light of freedom of choice and marketization. Assuming that student recruitment patterns, educational policy, options and choice affect each other in a complex process, it also provides a possible framework for a deepened understanding of student recruitment. The thesis presents results from four separate studies exploring how upper secondary programmes are shaped in national policy documents and how students with different social backgrounds respond to the implemented options. These studies explore policy documents from 1963 to 2008 as well as Swedish national registry data for upper secondary enrolment from 1990 to 2015. The results show that students’ programme choices are deeply stratified along similar lines in all cohorts, but also highlight alternative patterns that emerge in relation to organisational and societal shifts. In general, students from academic homes are continuously overrepresented in academic preparatory programmes and the distribution of students over different programmes is deeply gendered. Moreover, the changes that do occur appear to enforce rather than to counter recruitment biases. The findings also suggest that previous, policy informing, student recruitment research has not only had an evaluating function, but has also contributed to shaping upper secondary programmes. The analytical divides that emerge in policy papers (academic/vocational and science/social) are here shown to shape programmes that are entangled in prevailing power relations and to circumscribe students’ possibilities to choose. In addition, it is shown that the aggregations of data that previous research used as representations of these divides risk hiding other differentiating processes that potentially affect young peoples’ opportunities in life. Consequently, this thesis argues that social biases can be discerned and challenged by continuously revisiting the constructs that shape the understandings of what upper secondary education is – and can be. Parts of work I. Mellén, J. (2017). Rörlighet och selektion på en" öppen" gymnasiemarknad. Utbildning & Demokrati–tidskrift för didaktik och utbildningspolitik, 26(1), 133-157. II. Mellén, J. (manuscript). Education in demand, or a flash in the pan? Representations of desire in Swedish upper secondary school III. Mellén, J., & Angervall, P. (2020). Gender and choice: Differentiating options in Swedish upper secondary STEM programmes. Journal of Education Policy, 1-19. visa artikel IV. Mellén J., & Angervall, P. (under review).Exploring the Other: Analysing programme formations, recruitment patterns, and gender in Swedish upper secondary school.