School success is closely linked to intelligence but also to non-cognitive factors such as achievement motivation. The present study examines which non-cognitive factors predict secondary school grades and looks at reasons why female students tend to outperform their male counterparts. A sample of 554 German freshman students provided measures of general intelligence, achievement motivation, science course choice, self-efficacy, self-perceived academic achievement, and test anxiety. Results show that achievement motivation, self-perceived academic achievement, and sex significantly contribute to the final secondary school success above intelligence. Females' advantage in final secondary school grades becomes even larger after controlling for general intelligence. This advantage can be explained by females' higher achievement motivation. Showing more compensatory effort as well as self-control and taking more pride in their own productivity helps females to outperform their male counterparts at secondary school.