This research presents a new teaching design to be used in teaching training at the university (IUFM) in 2007-2010: the portfolio. This pedagogical innovation, associated with teacher training and linked to the evaluation of competency, has raised many questions on the capacity of portfolios to show, to assess and to validate the attainment of skills. Is there in particular a link between the reflective nature of portfolios and the attainment of professionnal skills? As regards methodology, this research is conducted with 40 portfolios and a reflection model, which is based on indicators defined in this study. The results show that if the link between the reflective nature of portfolios and the attainment of professionnal skills is proved, the inference isn’t confirmed.