Increases in adult stimulant prescribing pose a potential risk due to the higher prevalence of contraindicated conditions among this population. This study sought to identify patient, provider, and visit characteristics predictive of potentially inappropriate adult stimulant prescriptions. The proportion of potentially inappropriate adult stimulant prescriptions increased over time and with patient age. Visits to primary care providers were predictive of potentially inappropriate prescribing, and a history of substance abuse was predictive of new stimulant prescriptions; therefore, quality improvement interventions regarding safe stimulant prescribing practices may be warranted.