This study examined communication behaviors of children and adolescents with severe cognitive disabilities. Communication samples of 103 participants with severe or profound mental retardation, ages 3 to 15 years, were obtained through natural observations and structured one-to-one interactions. The communication samples were analyzed to determine primary expressive forms of communication, as well as degrees to which use of symbols, intentionality, social reciprocity, and complexity were apparent. From these data, seven Communication Profiles were distinguished to characterize levels of communicative competence within this population, ranging from basic reactions to complex interactions. Differences were noted in the patterns of communication forms and profiles between participants with severe versus profound mental retardation, but age differences (older versus younger individuals) were not observed. The potential use of the Communication Profiles as a conceptual framework to assess functional communication skills and consider meaningful intervention goals was discussed.