The transition to adult healthcare has been the subject of increased research and policy attention over many years. However, unmet needs of adolescent and young adults (AYAs) and their families continue to be documented, and universal implementation has yet to be realised. Therefore, it is pertinent to re-examine health transition in light of the principles of adolescent medicine from which it emerged, and consider this particular life transition in terms of a developmental milestone rather than a negotiation of structural boundaries between child and adult services. Health transitions are an integral part of AYA development and as such, occur alongside, and in connection with, a range of other important transitions that affect many other areas of life. In this paper, we discuss the interrelated nature of health transitions and AYA development; outline the underpinnings of a developmentally appropriate approach to transitional care; and consider the outcome measurement of such care based on existing evidence. A developmental approach has the potential to refocus transition on the fundamental principles of adolescent medicine, enabling health transition to be integrated along with other life transitions into routine AYA developmental assessments rather than being limited to the geographies of different healthcare settings and a potential health crisis.