Internationally, the attention being paid by governments to research education is growing in line with the increasing numbers of students undertaking research degrees. With this emphasis on research students it is, however, becoming clear that there is a specific category of research student that has been overlooked to the point that they are "invisible", in both policy and research terms: part-time students. This article addresses this gap by presenting an analysis of the satisfaction of Australian part-time research graduates, and a case study of predictors of their completion. The Australian example provides valuable lessons that can impact on the changes and features of research student programs in other countries. Part-time doctoral students were found to have faster completion times than full-time doctoral students, in equivalent-time terms. In terms of satisfaction with their student experience, part-time research graduates are less satisfied with the infrastructure support provided, and have a less favourable perception of the research climate of their department, than full-time research students. More specifically, the analyses in the case study highlight the varying issues and demands that are the best predictors of time to completion by mode of study for doctoral students. (Contains 4 tables.)