This study examined the relationship between the Peabody Picture Vocabulary Test—Third Edition (PPVT-III) and Wechsler Adult Intelligence Scale—Third Edition (WAIS-III) using 40 adults who ranged in age from 18 to 41 (mean age of 22 years). Participants were administered the PPVT-III and WAIS-III in counterbalanced fashion to control for order effects. Results revealed that the PPVT-III score was related to the WAIS-III Verbal IQ (VIQ) and Full Scale IQ (FSIQ) scores but unrelated to the Performance IQ (PIQ) score. In addition, analyses indicated that, while there were no significant differences between the PPVT-III score and WAIS-III mean FSIQ and PIQ scores, the PPVT-III mean score was significantly lower than the WAIS-III VIQ. Further analysis indicated that the PPVT-III adequately estimated WAIS-III FSIQ and VIQ scores for participants who were classified as Average or High Average on the WAIS-III. However, for participants in the Superior range, the PPVT-III tended to underestimate FSIQ and VIQ scores by approximately 10 points. © 2001 John Wiley & Sons, Inc. J Clin Psychol 57: 417–422, 2001.