Two field experiments examined if and how values affirmations can ameliorate stereotype threat-induced gender performance gaps in an international competitive business environment. Based on self-affirmation theory (Steele, 1988), we predicted that writing about personal values unrelated to the perceived threat would attenuate the gender performance gap. Study 1 found that an online assignment to write about one’s personal values (but not a similar writing assignment including organizational values) closed the gender gap in course grades by 89.0% among 423 Masters of Business Administration students (MBAs) at an international business school. Study 2 replicated this effect among 396 MBAs in a different cohort with random assignment and tested 3 related mediators (self-efficacy, self-doubt, and self-criticism). Personal values reflection (but not reflecting on values including those of the organization or writing about others’ values) reduced the gender gap by 66.5%, and there was a significant indirect effect through reduced self-doubt. These findings show that a brief personal values writing exercise can dramatically improve women’s performance in competitive environments where they are negatively stereotyped. The results also demonstrate that stereotype threat (Steele & Aronson, 1995) can occur within a largely non-American population with work experience and that affirming one’s core personal values (without organizational values) can ameliorate the threat.