The domain of transition studies has been drawing more and more scholarly attention and, as a result, its body of knowledge is rapidly growing. This raises new challenges as well as opportunities, not the least regarding the methodological and philosophical underpinnings of research in this domain. In this respect, transition research, as a relatively young field of inquiry, has been little concerned with methodological investigation and reflection. We propose a framework that enables this reflection: the so-called 'transition research onion'. Subsequently, we utilize this framework to systematically assess 217 peer-reviewed papers in the field of transition studies, to distill key methodological patterns and trends of the field. The findings suggest that the methodology of transition studies, in terms of depth and diversity, is underdeveloped. These insights serve to guide future research on transition processes.