During the transition between high school and college, there is an enormous decline in the number of women who pursue STEM (Science, Technology, Engineering, and Mathematics). Even in the STEM workforce, the gender gap is quite large. This results in a lot of wasted potential and talent that is needed to stay competitive in today's world. This thesis is divided into three parts: identifying a problem, analyzing possible causes, and highlighting various solutions. By using resources such as the Collegeboard, it is apparent that high schools girls over represent in AP and honors math and science classes and achieve just as much as their male counterparts. Due to various causes such as stereotyping, implicit bias, lesser developed spatial skills, lack of confidence, lack of female role models, and uncomfortable work environments, girls are deterred from pursuing STEM majors in college. Of those that do declare a major in STEM, many switch to a non-STEM major by the end of their first year. Even in the workforce, a majority of women in STEM leave midway through their career (after about 10 years). Although there are critics who claim that women do not have the biological ability to succeed in STEM, evidence proves otherwise. The underrepresentation of women in STEM fields has become such a known issue that there have been many recent programs and organizations put in place to encourage young women to pursue STEM. By evaluating the success of these programs and using them as a models, we can reduce the gender gap in STEM fields in the future.