Bibliography: leaves 131-155 / The central objective of the present research was to provide a better understanding of stereotype threat and its underlying effects on female high school students’ intention to major in Science, Technology, Engineering and Mathematics (STEM) fields. Specifically, the study investigated the intervening effects of mathematics/science self-efficacy and the conditional effects of perceived social support with regards to the implications of stereotype threat. For this reason, three studies were conducted. Participants were female (Study 1 – 3) and male (Study 1) high school students from Harer and Dire Dawa Regions, located in the Eastern part of Ethiopia. Study 1 provided evidence that both female and male participants were well aware of the existence of the negative stereotype about females’ mathematics/science ability. Participants reported that the Ethiopian society attributes less mathematics/science ability to females than to males. Although female participants were well aware of the existence of the negative stereotype about females’ mathematics and science ability, they did not endorse it. Study 2 showed experimentally that stereotype threat reduces indeed females’ intention to major in STEM fields. Moreover, Study 2 revealed that mathematics/science self-efficacy mediated the relationship between stereotype threat and females’ intention to major in STEM fields. Study 3 addressed the role of social support. The results revealed that female participants who felt socially supported in their intention to major in a STEM field were found to be resistant to the negative effects of stereotype threat. In other words, it is the interaction between stereotype threat and the lack of social support that reduces females' intention to major in STEM fields. The findings of the present study are discussed in relation to stereotype threat theory and related literature as well as in relation to potential educational interventions relevant for the Ethiopian context. / Psychology / D. Phil. (Psychology)