Stereotype threat theory (STT) presents a potential explanation for differences in achievement in math and science for women. Specifically, STT postulates 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 is the third in a series of studies examining the impact of ST on gender differences in science. The present study tested the impact of stereotype threat (ST) on gender differences in biology achievement, self-efficacy, motivation, and domain identification using a four-group, quasi-experimental design. 83 introductory-level college biology students were randomly assigned to 1 of 4 ST conditions including an explicit ST condition, an implicit ST condition, a reverse ST condition, and a nullified ST condition. Results indicated that there were no gender differences by ST condition; however, overall, the women identified more with the field.