Young children exhibit relatively high rates of emotion, self-regulation, and behavior control difficulties. Epidemiological studies in the United States and Europe have found that rates of diagnosable psychiatric disorders in 3-to 5-year-olds ranged from 7.1% (Wichstrøm et al., 2012) to 21.4% (Lavigne et al., 1996). Thus, up to one in five preschoolers may exhibit significant symptoms of emotion and behavior disorders. Rates vary as a function of diagnostic criteria, respondent (e.g., parent or teacher report), diagnostician (e.g., psychologist or pediatrician), and consideration of impairment beyond display of symptomatic behaviors. Although overall rates of disorder have varied across investigations, studies are consistent in finding highest prevalence for attentiondeficit/hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD), higher risk for disorder among boys, relatively strong associations across disorders (i.e., comorbidity), and very low rates of mental health service receipt (