This article conceptualises adult learners' professional growth in a tailored, work-related, teacher-qualification programme in physical education. The study data consisted of the reflectivelearning diaries of 20 adult learners during a 2-year tertiary and work-related teacher-qualification programme. The data were analysed using data-driven open coding analysis, which was conducted using the constant comparative method of the grounded theory approach. This article presents the horizontal dimensions (egocentric learner, researching professional and expert within society) and the vertical dimensions (transforming self-image, expanding professional self-expression and widening agency) of the adult learners' multifaceted professional growth process. In addition, the article discusses pedagogical implications in relation to developing teacher education in general and the education of physical education teachers in particular.