This paper presents the implementation of a portfolio for assessment purposes, with a group of primary school learners of English, aged 11-12. The focus of the portfolio is specific, concentrating on a purposeful and systematic collection of samples of students’ written language. The paper explores theories on portfolios as an alternative method of assessment and the benefits deriving from their use in the classroom. Moreover, it analyses all the stages of the organization of the learner portfolios from beginning to end. The findings shed light not only on positive outcomes but also possible problems. The paper discusses the implications of the study for classroom practice and provides suggestions for further experimentation.