Child neuropsychiatry encompasses childhood and adolescent psychiatric syndromes of neurobiological origins. It is an evolving discipline without consensus on its exact boundary. Given the inconsistencies, this chapter provides a historical perspective through which different conceptualizations of child neuropsychiatry can be understood and reconciled within the coherent whole. Four specific contrasting conditions are selected in this chapter to illustrate some key principles: attention-deficit/hyperactivity disorder (ADHD) as ‘a diffuse brain disorder’; childhood cranial tumours as ‘a localized brain disorder’; fetal alcohol spectrum disorders (FASD) as ‘a disorder of a specific cause’ represented by toxin exposure; and epilepsy as ‘a disorder of complex aetiology’. ADHD and cranial tumours represent the extremes of the polar divide between ‘a childhood neuropsychiatric disorder’ and ‘the neuropsychiatric manifestation of a childhood neurological disorder’. In contrast, FASD and epilepsy illustrate how specific and complex aetiology can present with a wide spectrum of psychiatric disorders. Atypical presentations of psychiatric symptoms, idiosyncratic treatment response, and ‘diagnostic overshadowing’ are also considered. The chapter emphasizes that child neuropsychiatric conditions are not fixed entities, despite conforming to diagnostic criteria stipulated by authoritative taxonomic systems. Rather, they are the results of the dynamic interplay between environmental factors, developmental maturity, mitigating factors, aberrant neural networks, and innate disease liability.