Introduction Students’ learning experience in socio scientific topics is among the factors that help them decide as a member of the society in the future and to help them use the skills they might need. Thus, in recent years, socioscientific has become one of the have aspects of science education that help raise responsible and sensitive citizens of the future. On the other hand, argumentation skills are among the high-level skills that should be given via science education. Moving from this fact, the purpose of this study has been set as analyzing the contribution of socioscientific issues based instruction approach (SIBIA) to development of argumentation skills of science teacher candidates, using mixed research method. Method The method used in the study is convergent or concurrent parallel design, which is one of the mixed research methods. The study group comprises a total of 82 teacher candidates (Experiment group = n:40, Control group=n:42) that are currently enrolled in 3rd year of Science Education of Elementary School Education Department of H.U. University School of Education. In the experiment group, each of the special science teaching methods were given based on SIBIA practices. And in the control group, science education was given via the special teaching methods, which are part of the regular teaching practices of the course. One of the existing routine practices in the control group is that SIBIA is implemented via narrative method over a four-hour period. Data Collection Tools The quantitative data of the study were collected using the Argumentation Skill Assessment (ASA) Scale developed by the authors. Student comments in ASA scale were converted into quantitative data using the rubric. In this study, in order to determine the concordance of the asymmetrical assessment scores, Kendall Tau c coefficient was calculated. In the study, scoring was conducted by the author and an instructor with experienced of argumentation. The concordance coefficient for the scores of both authors was calculated as Kendall Tau c=0,074. Inter-rater concordance was found to be at a satisfactory level (p<0,05). And as qualitative data collection tools; in-class observations, focus group interview and review of diaries of science teacher candidates. In the study, science teacher candidates were observed in the class environment where real instruction takes place. Observation was carried out using a video camera. No structured observation protocol was used. In addition, from those teacher candidates who gave consent in voluntary participation form, a experiment group was formed. Video camera footage last for around 10 hours. Video recordings were transcribed (converted into text) to be used in the analysis. For the focus group interview, a semi-structured form was prepared. The form which initially comprised three open-ended questions was sent to three field experts and corrections were made based on their feedback. Teacher candidates’ diaries were used as personal documents in the study. Diaries serve as a tool whereby the candidate teachers decide on their own frequency of writing. They were asked to note in these diaries, their feelings about and experiences related to the practices in the class. Results and Conclusion When the quantitative findings of the study are analyzed, a statistically significant difference was observed between the argumentation skills post test scores of the experiment and control groups [t(80)=2,36, p<0,05]. This difference is in favor of the experiment group whereby the socioscientific instruction-based approach is implemented. Giving the Special Teaching Methods course based on the socioscientific issues based approach results in more effective contribution to the development of the argumentation skills of the science teacher candidates compared to current routine practices. It can be argued that utilization of the methods whereby the candidate teachers are responsible from their own learning and where active teaching approaches are used, results in improved argumentation skills for the candidate teachers in science education. Looking at the qualitative results of the study, it is seen that the candidate teachers in the experiment group used argumentation expressions such as “defending one’s own view, discussion, raise a claim, justification, persuasion process and acceptance/rejection” (a total of 6 codes) in explaining the actions used in the learning process as part of the “socioscientific issue-based learning process”. On the other hand, candidate teachers in the control group used expressions such as “defending one’s own view and discussion (a total of 2 codes). When frequency values (fe>fc) and their comments regarding the learning process are analyzed, it was seen that the control group used much more limited expressions regarding the argumentation process. In conclusion, even though the candidate teachers are directed to the argumentation process in the socioscientific iss