Attention-deficit/hyperactivity disorder (ADHD) is a chronic and relatively common psychiatric condition characterized by a wide range of deficits in behavior control and attention (American Psychiatric Association, 2000). There are three subtypes of ADHD described by the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition, Text Revision (DSM-IV, TR; American Psychiatric Press, 2000): ADHD, Combined Type (ADHD/COM) is characterized by high levels of hyperactive/impulsive and attention problem symptoms; ADHD, Predominantly Inattentive Type (ADHD/I) refers to individuals with significant attention problem symptoms in the absence of clinically significant hyperactivity/impulsivity; and ADHD, Predominantly Hyperactive/Impulsive Type (ADHD/HI) refers to the least common subtype for individuals with substantial hyperactive/impulsive symptoms without attention problem symptoms. Children with ADHD typically experience problems related to academic performance, interactions with other family members, and peer relationships (Barkley, 2006; DuPaul & Stoner, 2003). Prevalence estimates of ADHD in school-age child samples in the United States range from 4-10% (Pliszka & AACAP Work Group on Quality Issues, 2007). Survey research has consistently indicated that ADHD is more frequently identified in boys than girls, with estimates ranging from three times more likely in community samples to upwards of nine times more frequent in clinical samples (Barkley, 2006; Biederman & Faraone, 2004). The majority of research related to ADHD has been completed with boys as the predominate members of study samples. However, over the past decade there have been increased efforts dedicated to learning about the characteristics of girls with ADHD, both in comparison to girls without this condition and in relation to boys with ADHD. Such research is essential in developing a more thorough understanding of the specific characteristics presented by girls with ADHD to help inform assessment and intervention efforts on behalf of this under-studied population. This is particularly important in the context of recent research findings establishing that, just as boys with ADHD, girls with this disorder compared with non-affected girls experience significant symptoms, comorbidity, and impairment across home, school, and social settings (Gaub & Carlson, 1997; Gershon, 2002; Hinshaw, 2002; Hinshaw and Blachman, 2005). Additionally, similar to boys with ADHD, a majority of girls diagnosed with ADHD continue to demonstrate significant symptoms and impairment due to their symptoms as they grow into adolescence (Hinshaw, Owen, Sami, Fargeon, 2006). There is a growing research base to support the conclusion that girls, much like boys, with ADHD and their families are coping with a serious, chronic condition that generally has a negative impact on multip le areas of functioning and development.