The alleged medical education continuum is interrupted by a number of major transitions. After starting medical school, the first transition students encounter is that from non-clinical to clinical training. The second transition is that of graduated student to junior doctor or specialist trainee, and the third concerns the specialist trainee's transition to medical specialist. As a first step towards a better understanding of the effects of transitions, this paper provides a critical overview of how these transitions have been conceptualised in the medical education domain. The findings are complemented with perspectives from the fields of transitional psychology and organisational socialisation. The transition into medical school is not reviewed. Using the term 'transition', six leading medical education journals were searched for relevant articles. A snowballing technique on the reference lists of the 44 relevant articles yielded 29 additional publications. Studies were reviewed and categorised as representing objectifying, clarifying, or descriptive and/or justifying research. When students enter clinical training, they need to relearn what they thought they knew and they must learn new things in a more self-directed way. As junior doctors or specialist trainees, their main challenges involve handling the many responsibilities that accompany the delivery of patient care while simultaneously learning from the process of providing that care. As medical specialists, new non-medical tasks and decisions on how to delegate responsibilities become issues. Research on transitions has objectified the challenges students and doctors face. Clarifying studies often lack conceptual frameworks that could help us to gain deeper insight into the observed phenomena. Psychology offers valuable theoretical perspectives that are applicable to medical education transitions. To transform a transition from a threat to a learning opportunity, medical education should assist students and doctors in developing the coping skills they need to effectively deal with the challenges presented by new environments. © Blackwell Publishing Ltd 2010.