© 2019, Ankara University. All rights reserved.The aim of the study is the improvement of argumentation based inquiry science teaching competencies of pre-service science teachers. In this study, the effects of argumentation-based inquiry teaching practices on teaching-learning conception and the ability to design experiments of the pre-service teacher were investigated. “Concurrent triangulation design” was used as mixed research method. The study was carried out for 14 weeks with 38 pre-service teachers who selected “Science Literacy” course for 2016-2017 academic years. Teaching-learning conception scale, experiment design studies and self-evaluations, semi-structured interview and reflective evaluation forms were used as the data collection tools. Although the quantitative findings reveal that there is no radical change in the teaching-learning conceptions of the pre-service teachers, the qualitative findings obtained showed that the pre-service teachers’ improved experiment design skills and created awareness about the teaching of scientific process skills. It also showed that pre-service teachers experienced a change towards an open-ended inquiry in experimental designs and this led to a number of changes and awareness in teaching-learning conception.