The purpose of this study was to understand enrollment and performance differences between male and females in higher level secondary STEM courses. This study analyzes performance and enrollment of 355,688 secondary students in higher level STEM courses. This research also enabled an exploration of country level differences. The enrollment research questions are evaluated using chi-square tests, frequency tables, and histograms. Performance research questions are analyzed with hierarchical linear regression and ANOVA with post hocs and Cohen's d effect size measures. Results suggest that females enroll much less frequently in higher level secondary STEM courses. Females and males perform equally well.