In this study, we investigate the impact of educational environments characterized by single-sex and co-educational settings on students' academic performance, communication skills, and self-confidence. The analysis encompassed 677 research articles, comprising 798 effect sizes, and involving a cumulative sample size of 1,179,558 participants. The existing literature presents inconclusive results regarding the effects of co-education on students' overall educational well-being. This research contributes to this ongoing debate by examining the impact of educational settings, specifically co-educational and single-sex environments, on academic achievement, communication skills, and self-confidence. Our findings indicate that the type of educational setting, whether co-educational or single-sex, does not exert a statistically significant impact on academic achievement, except in countries with a low educational attainment index, where students in co-educational settings achieve higher. Additionally, students in co-educational settings demonstrate better communication skills and higher self-confidence than their counterparts in single-sex schools. These results challenge the prevailing notion that single-sex education enhances girls' achievement and self-confidence while providing a safer environment for self-expression. In contrast, our data suggest that gender-segregated schools may not be the most conducive environments for girls to thrive both socially and academically, potentially due to the promotion of passive femininity within such institutions.