This research aims to identify the influences contributing to students' decisions to study medicine and to apply the findings to the design and targeting of outreach activities aimed at widening participation. Semi-structured interviews were carried out with 15 medical students at a UK medical school. Framework analysis was used to identify themes and subthemes and findings relating to becoming a doctor were analysed further in the context of a theory of career decision making. Five themes and subthemes were identified. We report the results for the 3 main aspects relating to becoming a doctor from the theme School to Medical School Transition: early motivation; inhibitory factors, and facilitating factors. Many students spoke about having always wanted to study medicine. Early exposure to the possibility of being a doctor allowed the idea to flourish and motivated students to achieve high academic goals. Inhibitory factors included discouragement from application by teachers on the grounds of not being 'doctor material'. Factors which facilitated access to medicine included the support of family members, particularly mothers, and other close friends, and having positive role models. Our analysis provides evidence of important factors in career decision making for medicine which can be used to inform widening participation interventions in 3 areas, namely, those of school support, home support and raising aspirations.