Describes observations made on 76 low-income children (aged 2.8-14.3 yrs) with a diagnosis of attention deficit hyperactivity disorder (ADHD). Data were gathered on each child at clinic visits and included medication status, and measures of inattention and defiance. Parents of 17% of children took a voluntary parenting skills course before medication was initiated. Statistical modeling was used to assess associations of medication usage and parenting classes with child inattention and defiance at follow up visits. Statistically significant beneficial associations were found between inattention and both treatment modalities (medication and parenting classes), and between defiance and parenting skills classes. These results support the efficacy of the treatment model used in the clinic for providing service to low-income children with ADHD.