Pediatric bipolar disorder, once thought rare, has gone through stages of conceptualization. DSM criteria were reinterpreted such that children and adolescents, particularly those with ADHD, were commonly diagnosed with bipolar disorder and thought to be atypical by adult standards. Research criteria separated pediatric bipolar patients into 3 phenotypes, including a research diagnosis of "severe mood dysregulation." DSM-5 largely maintained previous criteria for bipolar disorder at all ages and created a new diagnosis called "disruptive mood dysregulation disorder," categorized as a depressive disorder, for persistently angry or irritable patients with symptoms of childhood onset. However, the controversy regarding the diagnosis of pediatric bipolar disorder continues. Progress has been made in the classification of children and adolescents with mood symptoms who are predominantly irritable or angry, but lack of clarity remains regarding classification of children and adolescents with "symptoms characteristic of bipolar disorder" who do not meet criteria for bipolar I disorder, bipolar II disorder, or cyclothymia.