This paper analyses the development of the specialism of adolescent and young adult (AYA) cancer care via a Foucauldian lens to consider how knowledge and awareness have grown since questions were first raised about unmet needs of AYAs with cancer. The AYA specialism has gathered momentum over the last 30 years in the United Kingdom (UK) and is fast gathering pace internationally. Fundamental to this process has been the combined contribution from nursing and other health professionals, researchers, policy-makers and philanthropists. From an initial process of problematisation, through a gradual growth in empirical knowledge and resultant shifts in health policy, a new nexus of expertise has emerged that enabled AYA cancer care to become recognised as distinct from either child or adult oncology. Different stakeholders contributed to the discourses that have underpinned this development-a process likely to continue as it expands further. This paper draws on examples from the growth of the AYA specialism, the emergence of new professional roles and a growth in research. It illustrates how the coalescing of multiple perspectives allowed new discourses and, ultimately, new practices to be established that now have global impact.