Objective: The effectiveness of the Social Anxiety Program on Adolescent Twins investigated in this study. Method: The study is a mixed-method study using a one-group pretest-posttest design, together with the qualitative method. First, Intraclass Correlation Coefficient used to find out the concordance and differentiation level of the twins' social anxiety. Because monozygotic twins' concordance rate is higher than dizygotic twins, four pair female monozygotic twins aged 17-18 participated in the group. Wilcoxon Single Ranks Test used to analyze the experimental part of the research. Three sessions of focus groups held after the program. Content analysis techniques used as a qualitative analysis. Result: As a result, there was a statistically significant difference between pre/post-program. Since this difference was in favor of initial measurement, the program interpreted as being effective. Themes also supported the quantitative results. Conclusion: Findings obtained from both experimental and qualitative parts discussed. Suggestions provided for future researcher.