The purpose of this study was to examine the behavioral states of individual children for evidence of responsiveness within and without a multisensory environment (MSE). Three children in the age range of 3-10 years with severe multiple disabilities participated in the study. A single-system ABAB design was used. Participants' behavioral states, identified by indicators of alertness and responsiveness to context, were observed. Two participants demonstrated no change in their behavioral states with or without the MSE, suggesting that the environment did not have an effect on their responsiveness. One participant demonstrated a decrease in self-directed movement and an increase in visual attention with movement toward the MSE suggesting a more interactive shift in this participant's response to the environment. When symbolic or consistent methods of communication are absent, observation of behavioral state may provide occupational therapists an objective means of insight into the experiences of children with severe disabilities. (Contains 3 figures.)