This paper presents evidence on linear, nonlinear and cumulative gender peer effects on test scores. The study utilizes exceptional Swedish data containing the history of the gender composition of students’ classrooms from 1st to 9th grade. The analysis builds on school fixed effects, with the added advantage of observing within-school variation in gender composition across actual classrooms.  In contrast to what is often suggested in the literature, results show that gender composition does not uniformly impact boys and girls. More female-dominated classrooms slightly increase girls’ and decrease boys’ test scores, but these effects mainly impact students in classrooms with very skewed gender distributions. Moreover, effect sizes are very small, suggesting that classroom gender composition ought not be a primary policy concern, except when imbalances are large and cumulatively sustained. Findings also underscore the importance of accounting for non-linearities and cumulative effects in research on gender peer effects.

The gender gap in competitiveness is argued to explain gender differences in later life outcomes, including career choices and the gender wage gap. In experimental settings, a prevalent explanation attributes this gap to males being more (over)confident than females (we call this the compositional channel). While our lab-in-the-field study using data from students in 53 classrooms (N > 1000) reproduces this finding, it also uncovers a second, potentially more impactful channel of confidence contributing to the gender gap in competitiveness (the preference channel). To disentangle the two channels, we propose a more precise measure of confidence based on whether the subjects’ believed performance rank exceeds, coincides with or falls short of their actual performance in a real-effort task. We label categories of this Guessed - Actual Performance (GAP) difference as overconfident, realistic or underconfident, respectively. Surprisingly, there is no gender difference in competitiveness within the over- and underconfident subgroups, while a significant gender gap exists among the realistic. So, even if both genders had the same level of confidence, a persistent gender gap in preference (or taste) for competition would remain in the realistic group. This finding is robust across all specifications, challenging previous theories about the overconfidence of men being the main driver of the relationship between confidence and the gender gap in competition.

Academic self-concept and interests are important predictors of educational choices and have also been linked to gender differences in these choices primarily at the post-secondary level. However, our knowledge on how these motivational factors form decisions at the transition to upper secondary education is scarce. This paper first shows how subject-specific self-concept and interests affect upper secondary program choices by disentangling their net effect from the effect of prior school achievement. Second, it also analyzes if gender differences in these motivational factors contribute to the gender gap in upper secondary program choices (mediation) and whether there are gender differences in how achievement, motivation and choices relate to each other (moderation). The study uses survey data linked to Swedish register data and applies structural equation models to perform path analysis. Results indicate that the motivational factors not only predict the choice outcomes well but they also explain a large part of the gender gap in STEM program choice. Besides, results indicate gender differences in how achievement forms the motivational factors.