Inclusion Criteria:  Meets research criteria for a diagnosis of ADHD based on the Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS) Has never taken stimulant medication or has had at least a 6 week 'wash-out' period from stimulant medicines not related to enrollment in the study.  Exclusion Criteria:  Is currently taking stimulant medications or has taken stimulant medications within the last 6 weeks Allergy to dogs Significant fear of dogs Family history or history of cruelty to animals Meets research criteria for a diagnosis of Autism Spectrum Disorder (ASD) based on the K-SADS and SRS-2 total raw score in the 'severe range' Meets research criteria for a diagnosis of Major Depressive Disorder on the K-SADS Meets research criteria for a diagnosis of Schizophrenia on the K-SADS