In science, technology, engineering, and mathematics (STEM) education, producing high level talent and increasing equity of access and engagement are prominent but sometimes conflicting policy directives. Yet, retention and persistence are important outcomes both for the production of elite talent and for promoting equity within STEM fields. This dissertation investigates the effects of policy on student persistence in Finland, Sweden and the United States.

Drawing on interviews with upper-secondary school students and teachers (Finland: 26 students, 8 teachers; Sweden: 29 students and 10 teachers; United States: 19 students, 2 mentors) and surveys (Finland: 255 students, Sweden: 130 students, United States: 288 students), this study investigates the effects that different structures (including contrasting policies of stratification and differentiation, specialist magnet schools and enrichment programmes) have on students’ intentions to persist in STEM fields.

This study supports the theory that educational policies mediate student persistence both through structural possibility, and through the development of students’ identities and non-cognitive skills. Here, non-cognitive skills (such as self-efficacy and self-concept) are considered part of an ‘adaptive habitus’ and a latent variable comprised of domain-specific non-cognitive skills is used in models of student persistence. The models illustrate the do- main specific interactions of educational structures, student background, adaptive habitus and student persistence.

Analysis of the interviews further explores these relationships, suggesting the importance of programmes that include exposure to challenging real-world STEM learning and interaction with STEM professionals, and that such features are effective in part because they foster an adaptive habitus towards STEM fields. The policy implications for both efficiency and equity are considered.

A framework of Mechanism, Transparency and Permeability is introduced for analysing the effects of policies on efficiency and equity. Drawing on the interviews, this framework is used to give a comparative characterisation of the educational systems Finland, Sweden and the United States. Permeability is highlighted as particularly important for retention and persistence, and a key consideration for educational policies that seek to produce elite talent, and promote equity in STEM fields.