A search for classification systems is a pivotal component of study and development of a ground-based theory in human and behavioral sciences. Determining classification systems is one of the basic components for advancing a better understanding of the genome of human communication in general and of communication disorders, in particular, which is required for validating an assessment, proposing the treatment, and specifically, the prevention of the communication disorders. This entry describes systems of classification in language and their importance for effective communication. It also discusses classification of communication disorders and specific language impairments.