This paper reports on the use of portfolios in a continuing professional development programme to advance teachers’ skills in their pedagogy of argumentation. The programme adopted a cyclical process of expert input- teacher practice- sharing practice, in order for professional learning to include reflective analysis of growing accomplishment. Accomplishment was initially defined according to previous research and development on the teaching of argumentation, but was redefined during the programme as teachers shared practice and discussed their achievements. Portfolios were used to help teachers apply their learning, collate evidence of their accomplishment and share reflective analysis of practice with other colleagues on the programme. The paper includes extracts of two teachers’ portfolios; these provide evidence of each teacher’s developing accomplishment in the teaching of argumentation. Portfolios are idiosyncratic and are constructed according to an individual teacher’s motivations, interpretations and situations. Teachers need structure and guidance in creating purposeful portfolios that enhance reflective practice