Guidelines for the diagnosis, evaluation and intervention with Specific Language Impairment (SLI) children are provided. Unresolved issues concerning the diagnosis of SLI children are discussed, pointing out how some authors refer only to exclusionary criteria, while others also adopt inclusionary criteria. An initial delay in language development may persist and eventually result in atypical development and subsequently in Specific Language Impairment. The evaluation of language abilities must be conducted in several domains (phonological, morphosyntactic, semantic and pragmatic), and in different contexts. The evaluation must be continuously updated in order to allow for possible modifications of the diagnosis and of the intervention protocols. The necessity of early intervention is underscored.