This paper seeks to resolve certain questions pertaining to the relationship between gender and second language vocabulary knowledge. One question we examine is whether female and male ESL students at the University of California at Irvine differ significantly in their knowledge of academic vocabulary in English as measured by scores on the Test of Academic Lexicon (TAL). One hundred ninety-two freshman university ESL students participated in the study. A t test, used to investigate differences in the TAL scores of males and females, reveals that the males performed better on the TAL than the females (t = 3.32, p = .001). Analyses of covariance were used to examine questions pertaining to the effect of gender on the TAL, controlling for the possible effects of the students' verbal Scholastic Aptitude Test (SAT) scores, length of residence in the United States, and age of arrival in the United States. In all cases, gender remains significantly related to the results of the TAL when controlling for the other variable: for verbal SAT scores, F(1,181) = 5.86, p < .05; for length of residence, F(1,187) = 9.64, p < .01; and for age of arrival in the United States, F(1,185) = 10.22, p < .005. Neither the present study nor the gender literature reviewed suggests that gender itself causes differences in the TAL scores. In analyzing the results, we consider possible explanations for the males' better TAL scores related to reading habits, interactional styles, educational backgrounds, and cultures.