Communication programming for individuals with severe disabilities often does not meet the requirements ofbest practices. One reason for this is that a dominant psycholinguistic model, the Dictionary + Rules model (pronounced "Dictionary plus Rules model') provides a theoretical base that is inconsistent with best practices. In fact, the model's perspective on language and communication may be sufficiently inadequate and misleading to warrant not using this model as an approach to understanding the fundamental mechanisms underlying communicative behavior. An alternative model, the Context x Memory model (pronounced "Context times Memory model') is described. This model is shown to support a view ofcommunication and language that is consistent with emerging best practices and has new implications for language instruction. Adoption of this second model represents a paradigm shift, because this model's perspective on the relationship between cognition and language differs from that of the dominant model. DESCRIPTORS: assessment, communication assessment and training, language assessment and intervention, language theory, natural environmentCommunication is the transmission of information between two or more individuals (Green & Marler, 1979;Sanders, 1976;Owens, 1992). Communication skills are fundamental to participation within our culThis paper is based in large measure on a series of four papers (Jackson, 1992a(Jackson, , 1992b(Jackson, , 1992c(Jackson, , 1992d) that provide a comprehensive and detailed presentation of the theoretical and practical issues discussed here, including broader descriptions and reinterpretations of the concept of rule-governed behavior. Rhine for their invaluable comments and suggestions. He also thanks the graduate seminar students of the summer, 1991 for their emotional and intellectual support when this work was in a critical stage of development.143 ture and society. The competent communicator effectively uses language and related skillsto accessactivities and control resources, establish and maintain relationships, and support others in their realization of intentions and needs.Developing a repertoire of effective communication skills, ensuring access to a functional communication system, and supporting communication skill use are primary objectives of instruction with individuals who have severe disabilities. A primary concern facing the field is ensuring that practitioners use best practices in communication programming.' Actual intervention practices often reflect clinical and educational procedures that are based on older models of service delivery that are not consistent with best practices (Eger, 1992;Giangreco, 1990;Rowland, 1990).The lag between best practice and typical practice may result from the rapid changes that are occurring in instructional technology. Procedures in which discrete response topographies were taught in isolated settings