The study investigated the effect of self-assessment via European Language Portfolio (ELP), unit based checklist and learner style inventory on students' attitudes towards learning English. The study was conducted at Bülent Ecevit University the School of Foreign Languages Basic English Deparment in the 2016-2017 academic year. The study also examined the attitudes of students and teachers towards the ELP and its implementation into the curriculum.Two data collection instruments were employed in this study. Semi-structured interviews were conducted with thirty students and five teachers. Attitude questionnaires were given to the students.Both the qualitative and quantitative results of the study indicated that the ELP, learner style inventory and unit based checklists are tools which can promote selfassessment on the condition that they are used effectively both by the teachers and students and as a consequence they support having more positive attitudes towards learning English. Additionally, it was found that the students felt positive towards the ELP and working with it as far as they used it correctly in their classes as part of the curriculum.In addition, the findings of the study indicated that both the teachers and the students believed that the ELP was a tool for self-assessment; however, the implementation of the ELP in the curriculum of the School of Foreign Languages at Bülent Ecevit University needs support since the ELP has only been newly introduced in Turkey as well and the teachers have very little information about the use and effectiveness of the ELP in language learning. However, this study showed that the ELP could be used as a tool to promote self-assessment and to create learnercentered classrooms in Turkey. Thus, promoting self-assessment is not as difficult as it is thought to be, and the ELP, learner style inventory and the unit based checklists are important tools to promote it.