Speech disabilities (articulation deficits) and language disorders—expressive (vocabulary) receptive (language comprehension) are not uncommon in children. An overview of these alongwith a global description of the impairment of communication as well as clinical characteristics of language developmental disorders are presented in this article. The diagnostic tables, which are applied in the European and Anglo-American speech areas ICD-10 and DSM-IV, have been explained and compared. Because of their strengths and weaknesses an alternative classification of language and speech developmental disorders is proposed, which allows a differentiation between expressive and receptive language capabilities with regard to the semantic and the morphological/syntac domains. Prevalence and comorbidity rates, psychosocial influences, biological factors and the biological social interaction have been discussed. The necessity of the use of standardized examinations is emphasised. General logopaedic treatment paradigms, specific therapy concepts and an overview of prognosis have been described.