This study aimed to examine the effect of test format on test performance by comparing Multiple Choice (MC) and Constructed Response (CR) vocabulary tests in an EFL setting. Also, this paper investigated the function of gender in MC and CR vocabulary measures. To this end, five 20-item stem-equivalent vocabulary tests (CR, and 3-, 4-, 5-, and 6-option MC) were administered to 243 (132 male and 111 female) pre-intermediate students. Results of the study revealed that MC tests were easier than CR. Results indicated a gender bias, in that, males scored better than females in all versions of MC tests while females outperformed males in CR. The findings implied that testers should consider the effect of test format while assessing vocabulary knowledge and use a combination of test formats (MC and CR) in vocabulary assessment to reduce gender bias and format effect.