Interjections are linguistic expressions used to express emotion and they can also be used to convey the attitude or mental state of a speaker. As well as being an integral part of language, interjections play an important role in communication. Deficits in social communication and social interaction form part of the triad of impairments in Autism Spectrum Disorder, and Language Disorder impacts upon the communicative abilities of a person. This study is the first to investigate the use of interjections by children and adolescents with Autism Spectrum Disorder, Developmental Language Disorder, and a typically developing cohort. To date, the study of interjections is extremely limited in scope as research within this area has been overlooked by linguists. This book strives to address this issue, and a novel approach to eliciting interjections through storytelling and spontaneous play is introduced. The preliminary study is discussed at length along with its findings, but there are also a range of topics covered within the book including neurology, emotions, theory of mind, language acquisition, and interjectional usage.