The purpose of the current study is to evaluate the development of scientific reasoning skills through activities conducted in the scientific reasoning skills course, which pre-service science teachers take as a required course. Participants (N = 53) are 3rd year students of the Department of Science Teaching. The study employed a mixed research method using quantitative and qualitative methods together. In the quantitative part of the study, the single group pre-test-post-test design was used, and in the qualitative part of the study, the case study design was used. Because of the activities conducted in the study, a significant improvement was observed in the scientific reasoning skills of the pre-service teachers. When the pre-service teachers' opinions were evaluated, themes including their suggestions on the contributions of the course to them, on the course content and for the improvement of the course were obtained.