A total of 52 Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV) protocols, administered by graduate students were examined to obtain data on the type and frequency of examiner errors, the impact of errors on resultant test scores as well as improvement rate over the course of two years in training. Findings were consistent with previous research on graduate students' errors on the Wechsler scales. Students committed errors on 98% of the protocols with an average of 13.3 errors per protocol. The five most common errors committed by graduate students on core subtests across all 52 protocols were calculating subtest raw scores incorrectly, scoring individual items incorrectly, failure to query, failure to provide correct prompts and failure to record responses verbatim. Errors resulted in inaccurate Full Scale IQ and Index scores, with the Full Scale IQ and Verbal Comprehension Index most frequently affected. Errors significantly improved across the first two practice administrations with further improvements on the third and fourth protocols administered the following year. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]