In this study, our aim was to determine the extent to which family physicians in Minnesota follow the American Academy of Pediatrics (AAP) guideline in the assessment and diagnosis of attention-deficit/hyperactivity disorder (ADHD) in school-aged children and to identify barriers to using the guideline. We surveyed 1,000 randomly chosen members of the Minnesota Academy of Family Physicians. Of 303 respondents, 36% always referred children for a diagnosis and 99.7% referred children for a diagnosis of ADHD some of the time. Fifty-four percent were unaware of the AAP guideline. However, among those who said they evaluate children for ADHD, most followed the criteria in the AAP guideline. For example, most family physicians (97%) used a child's response to stimulant medication in their assessment. Respondents also said that barriers to ADHD assessment included lack of reimbursement and training.