Stereotype threat theory (STT) offers one explanation for achievement differences in math and science for both women and minority students. Specifically, STT posits that the perceived risk of confirming a negative stereotype about an individual's identity group acts as a psychological burden that negatively impacts performance. This study examined the impact of stereotype threat (ST) on gender differences in chemistry achievement, self-efficacy, and test-anxiety using a four-group, quasi-experimental design. 153 introductory-level college chemistry students were randomly assigned to one of four ST conditions including an explicit ST condition, an implicit ST condition, a reverse ST condition, and a nullified condition. Results indicated that there were no gender differences by ST condition; however, overall, the men had higher self-efficacy and lower test-anxiety than the women. An analysis of open-ended questions asking students about their intent to major in chemistry, beliefs regarding barriers to their achievement on the chemistry test, and gender differences in opportunities and mental capacity to achieve in chemistry provided insight into the quantitative results. Implications of our findings for future research on ST are discussed.