SummaryDeafness does not in itself cause emotional/behavioural or cognitive problems or psychiatric disorders. However, children with hearing impairment are at greater risk of developing emotional/behavioural problems and neurodevelopmental disorders. The incidence of both seems to be higher in deaf children from hearing families. Most prelingual deafness is caused by recessive genes; hence, most deaf individuals come from hearing families, the majority of whom do not use sign language. Numerous studies, in both hearing and deaf populations, show how the lack of access to language has an impact on the emotional development of children. This article focuses on the mechanisms by which early language deprivation mediates emotional/behavioural difficulties and consequent emotional dysregulation, and may produce behaviours and symptoms that can be misdiagnosed as neurodevelopmental disorders in deaf children and adolescents (from infancy to 18 years of age).