Abstract: This research was conducted to survey the assessment and diagnostic practices of school psychologists who assess individuals referred for Attention-Deficit/Hyperactivity Disorder (ADHD). Results showed that a substantial number of school psychologists routinely provide ADHD assessments despite concerns about the quality of the psychological instruments available to them or a lack of an agreed-upon gold standard for ADHD assessment. Participants reported that ADHD-related referrals were accurate approximately 65% of the time, and teachers were rated as both the most common and accurate of all referral sources. Most of the school psychologists used the Wechsler Intelligence Scale for Children, the Behavior Assessment System for Children, the Connors' Rating Scales, and the Woodcock Johnson Tests of Achievement when assessing for ADHD, but only one test was recognized as above average for psychometric quality, whereas ten of the most commonly used tests for ADHD assessment were rated as below average in terms of psychometric properties. Finally, the most popular rationale offered for test use was differential diagnosis (41%), which was offered more than twice as frequently than any other option. Results are discussed in terms of implications for training and future research, current professional practice standards, and clinical decision-making issues.