Objective We implemented a parent–teacher Vanderbilt agreement program to increase return rates of Vanderbilt assessment scales for children in our primary care practice, and compared the assessment return rate before and after agreement signature. Methods We retrospectively reviewed children diagnosed with attention-deficit/hyperactivity disorder (ADHD) who had a signed Vanderbilt agreement and were under continuous care at our clinic. Return rates were compared 1 year before and 1 year after the agreement date. Results Among 195 children, prior to the agreement, 71% returned teacher assessments, and 59% returned parent forms; after the intervention, assessment rates were not significantly different (76%, p = .255; and 65%, p = .185, respectively). The median number of returned assessments increased after the agreement. Conclusions Lack of documented parent and teacher Vanderbilt assessments remain a barrier to appropriate management of ADHD. Improving the rate of assessments returned is an important outcome for treating ADHD in the primary care setting.