This paper reviews a range of challenges and tensions experienced when using portfolios for learning as well as for summative assessment in the context of continuing professional learning in academic development programmes. While portfolios are becoming increasingly prominent, the details of how they are used are under-examined; they are often simply assumed to be an appropriate tool. However, it is important that, as practitioners, we are able to justify our own assessment practices and convey our expectations to our participants, who may be unfamiliar with the demands of a reflective portfolio. In this paper we explore some of the appeal as well as the difficulties of using portfolios, many of which arise from the fact that portfolios are often simultaneously used for summative and formative purposes. We suggest how the challenges sometimes experienced with portfolio assessment can be addressed by course conveners.