An e-portfolio system was introduced into the personal and professional development curriculum at the University of Western Sydney School of Medicine (UWSSoM) during 2011 and 2013. Adopting the methodology of Design-Based Research and an interpretive framework informed by Activity Theory we developed a set of educational design principles based on the analysis of the use of the e-portfolio system by students and tutors. These principles contain a range of insights applicable to the local context and may also be of interest to curriculum designers working in other domains