The purpose of this study is to examine the critical thinking skills of preservice science teachers in terms of various variables (gender, grade level, academic grade point average, participation in activities) and their opinions. In the research, sequential explanatory design, which is one of the mixed method research designs, was used. The study was carried out with 200 preservice teachers studying at Science Education Department of a state university chosen at Cappadocia region of Turkey. Interviews were conducted with low-level (f = 7) and high-level (f = 7) preservice teachers selected by means of purposive sampling method from these pre-service teachers participating in the study. Regarding the quantitative and qualitative data obtained; it has been determined that the critical thinking skills of the preservice teachers did not show any significant difference according to gender, grade level and academic grade point average, but there was a significant difference in terms of the activities performed. Preservice teachers expressed that their family structures, social environments in which they interact, and characteristic features were said to be effective in the development of critical thinking skills. Regarding the findings, it has been concluded that trainings that will evoke higher level skills such as critical thinking skills in universities can be effective, but the social and cultural background of the preservice teachers are also effective on these skills. It is recommended to prepare contents that enhance higher level skills such as critical thinking skills as well as education for pedagogy or content knowledge given at universities.