This article presents the findings of a seven-week case study which aimed to identify the benefits of self-assessment in EFL writing classes at tertiary level. The study was conducted with 17 B1- English language proficiency level students studying at an English preparatory programme of a foundation university. First, the students were introduced to using rubrics to assess a written product. Then, each week after students composed a writing, a paragraph for the first three weeks and an essay for the remaining (...) four weeks, the students were asked to assess their own writing by using the relevant rubric and filling in the self-assessment form. In addition, a questionnaire was conducted at the beginning of the study to investigate whether the students could identify their own strengths and weaknesses in writing, whether they could make sense of the criteria that are used for writing quizzes, and whether they made sense of the feedback given by the teachers for their writings. The same questionnaire was conducted again on the last day of the research to check whether the participants changed their opinions. The results revealed that the students improved their understanding of the rubrics over time by practice, they felt more responsible for their own learning, they were able to reflect on their own performance, and they became more autonomous learners. (shrink)