Performance on the Yes/No test (Huibregtse et al., 2002) was assessed as a predictor of scores on the Vocabulary Levels Test (VLT), a standard test of receptive second language (L2) vocabulary knowledge (Nation, 1990). The use of identical items on both tests allowed a direct comparison of test performance, with alternative methods for scoring the Yes/No test also examined (Huibregtse et al., 2002). Overall, performance on both tests by English L2 university students ( n - 36) was similar. Mean test accuracy on the various Yes/No methods ranged from 76-82%, comparable to VLT performance at 83%. However, paired t-tests showed the scoring methods used to correct raw hit performance increased the difference between the Yes/No test and criterion VLT scores to some degree. All Yes/No scores were strong predictors of VLT performance, regardless of method used, r = .8. Raw hit rate was the best predictor of VLT performance, due in part to the >5% false alarm rate. The low false alarm rate may be due to the participants, drawn primarily from non-Latin alphabet first languages (L1s), and the nature of the instructions. The results indicate the Yes/No test is a valid measure of the type of L2 vocabulary knowledge assessed by the VLT, with implications for classroom application.