Using the International Association for the Evaluation of Educational Achievement's (IEA's) Trends in International Mathematics and Science Study (TIMSS) 2015 data, this brief explores the relationship between teachers' gender and students' mathematics and science achievement, as well as gender differences in science and mathematics teachers' self-efficacy and its relation to job satisfaction. We find that there is no direct relationship between the gender of the teacher and students' performance in science and mathematics. Grade 4 and 8 students taught by female teachers perform just as well in science and mathematics than their peers taught by male teachers. Yet, results show that female science and mathematics teachers have less self-efficacy than their male counterparts. Additionally, the relationship between self-efficacy and job satisfaction is positive, and this relation is particularly strong for female science and mathematics teachers. The brief concludes with a discussion of the potential implications of these results, some suggested actions to build female science and mathematics teachers' self-efficacy, and areas for further research.