This article addresses the issue of in-service teacher education, which has become a focus of international education policy attention in recent years. Professional learning (PL) is often envisioned by policymakers as a mechanism by which the professionalism of the teaching workforce can be remodelled and refreshed. It offers a means to enhance teachers' professional efficacy and, consequently, the outcomes of students. The article examines the case of England, and takes a single subject area (modern foreign languages) as the context in which to explore teachers' PL experiences over the course of one calendar year. Data tracking the PL priorities and experiences of 54 teachers clustered in 14 state school languages departments were collected via four iterations of an online questionnaire. This was followed by in-depth semi-structured interviews with heads of department in six of the schools, enabling a process of triangulation. Analysis shows very limited engagement in PL activities of the kind identified in previous literature as effective in impacting student outcomes. In all the schools, teachers' PL experiences were shaped by a sharp focus on instrumental organizational aims related to the introduction of new examination specifications and curricula, reducing available time and resources for the pursuit of other development goals. A large amount of the variance in teachers' reported engagement in PL activities known to be effective can be explained by school membership. Heads of department recognize their role in shielding colleagues from excessive workload and promoting collaborative PL. However, they report varying degrees of agency in addressing contextual barriers to achieving these aims. In contexts where teachers report high levels of stress, this is associated with lower professional self-efficacy, engagement and intention to remain in the profession.