This paper on intervention research critically reviews evaluations of experimental procedures designed to effect changes in the language development of disadvantaged children. It includes a summary of intervention projects and survey of present knowledge and theory about language which constitute the rationale for such projects. Specific recommendations are made for the application of the findings in broader educational contexts. Although many educators agree that language is one specific area in which disadvantaged children need to catch up, they often disagree on the nature, importance, and antecedents of these deficiencies in language. The paper includes discussion of alternative views of language, methods of language assessment (language production, comprehension assessment, and standardized testing), a selective review of subcultural language differences, and a review of language intervention research (Project Head Start, Bereiter-Engelmann Program, etc.). In addition, the authors recommend specific educational practices. (Authors/JW)