The importance of gender equity in science, technology, engineering, and mathematics (STEM) has continued to be an area of national concern. Research examining women's experiences in STEM has highlighted several factors, both at the student- and institutional-level, that contribute to women's continued underrepresentation in STEM, especially in fields such as engineering and computer science (NSF, 2009). However, few of these studies take into account the effect of peer relationships on students' experiences in STEM. As friendships have been shown to have particular significance in the lives of women, it seems clear that research on women's underrepresentation in STEM would benefit from an examination of the relationships between friendships and academic and social outcomes. Data for this study are drawn from UCLA's Cooperative Institutional Research Program's 1996 Freshman Survey and the 2000 College Student Survey (CSS). The 2000 CSS includes a key variable which asks students about the proportion of close friends they have of a particular social or demographic group, including one's major. The study sample includes data for 1,478 women and 1,406 men, all of whom completed both surveys and indicated on the 2000 CSS that they will graduate with a bachelor's degree in a STEM field. Findings from this investigation confirm that same-major friends can positively impact STEM students' academic and social outcomes. Regression results indicate that, for men, having higher proportions of same-major friends corresponds to an increased likelihood of aspiring to have a STEM career and higher levels of science identity goals and scientific orientation. However for women, having more same-major friends was significantly related only to an increase in scientific orientation. While it was unexpected that same-major friendships would have a significant relationship with more outcomes for men than women, this work does indicate a small but positive impact of same-major friends for STEM students. However, same-major friends did not impact academic self-confidence and psychological well-being for this study sample. Based on these findings, recommendations for faculty, student affairs practitioners and administrators on encouraging friendship formation among STEM students are posed, as well as suggestions for future research to expand on our knowledge of peel relationships and STEM student experiences in college. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]