This study used qualitative constructivist grounded theory research methods to explore with focus groups of 16 racial/ethnic minority undergraduates underrepresented in STEM (science, technology, engineering, and math) their experiences of microaggressions, sense of belonging in STEM, and their strategies to negotiate these experiences. Participants shared striking examples of their experiences with subtle yet frequent racial/ethnic microaggressions, though often unintentional, that influenced their sense of belonging in college and STEM fields. They also shared examples of strategies that were most useful in navigating microaggressions and persisting in their STEM academic pursuits. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]