Objective: To compare performance of the newest vital sign (NVS) with existing literacy measures. Methods: We administered the NVS and REALM to 129 patients, and NVS and S-TOFHLA to 119 patients all in public clinics. Results: The NVS demonstrated high sensitivity for detecting limited literacy and moderate specificity (area under the receiver operating characteristic [AUROC] curve 0.71-0.73). The NVS was less effective than the S-TOFHLA for predicting health outcomes. Conclusion: The NVS is able to identify patients with limited literacy skills, but may misclassify those with adequate literacy according to the REALM and S-TOFHLA. NVS scores were not associated with health outcomes.