This research project sets out to investigate the extent to which boys’ and girls’ self-efficacy beliefs differ. The researcher first investigated the current research on the topic and found that most of the research suggests that boys are more confident in their mathematics ability than girls are. They are also more likely to want to study mathematics further or include it in their career in the future. It also investigates students' opinions about gender in mathematics and found that both boys and girls frequently think that boys are better at mathematics. To gain data the researcher gave students in a mainstream secondary school a questionnaire to complete and then interviewed some of these students. The findings revealed that it is not always the case that boys have higher self-efficacy beliefs than girls as many of the boys in the study had low self-confidence and were not keen to study mathematics after school. Additionally, all the students in the study did not believe that boys were better than girls at maths and thought that gender was not a factor in mathematics ability as they are equal in their abilities.