Structural inequalities and stereotypes are held out as explanations for gender differences in reported levels of confidence. However, while it is reported that in the absence of stereotypes women and men should possess identical levels of self-confidence, no study to date has tested this hypothesis. Single sex schools were identified as an environment where structural bias might be mitigated. From a survey of 9,414 Australian adolescents aged 13-17 years attending single sex high schools, no significant difference in overall self-efficacy was identified between genders. Overall, by age cohort there was no significant difference between boys' and girls' self-efficacy, with a minor exception of the 15 years cohort. Self-efficacy levels were linked to participation in team sport and undertaking leadership roles. The study provides the first large scale study that demonstrates that women are no less confident than men under conditions where gendered structures are mitigated by their environment.