To date, the majority of research on Attention-Deficit/Hyperactivity Disorder (ADHD) has been completed with boys as the predominate participants in study samples. Over the past decade there has been increased attention focused on the characteristics and needs of girls with ADHD. Although much of the research comparing boys and girls with ADHD indicates that both experience significant symptoms and impairment, a growing body of study suggests some important gender differences. The purpose of this paper is to summarize the findings of research examining girls with ADHD and highlight key characteristics that can inform clinical practice. A case study is presented to illustrate the unique pattern of symptoms, associated problems, and functional impairment for girls with ADHD. (Contains 2 tables.)