The interpretation of cognitive test scores often leads to decisions concerning the diagnosis, educational placement, and types of interventions used for children. Therefore, it is important that practitioners administer and score cognitive tests without error. This study assesses the frequency and types of examiner errors that occur during the administration and scoring of the Woodcock-Johnson III Tests of Cognitive Abilities (WJ III COG). Data from 36 graduate students across 108 test records revealed a total of 500 errors across all records. Further analyses indicated three frequently occurring errors, including the use of incorrect ceilings, failure to record errors, and failure to encircle the correct row for the total number correct. The results of this study may be used to inform training programs so that appropriate steps can be taken to decrease the number of examiner errors on the WJ III COG and similar cognitive test batteries. (Contains 4 tables and 2 footnotes.)