The present study examined the effects of communication mode (oral vs. oral plus manual) and level of communicative competence (high vs. low) on profoundly deaf preschool children's play interactions with their hearing mothers. The sample consisted of 28 dyads equally divided into groups of oral and simultaneous (oral plus manual) communicators that were matched on audiologic and demographic variables. Videotapes of free play interaction were subjected to an interaction analysis. This analysis examined behavior at the level of the dyad or interaction rather than at the level of individuals. The duration and complexity of interaction were strongly affected by both the method and level of communication. Simultaneous dyads had interactions that were longer, more complex, and contained more cooperation and positive affect than did oral dyads. The role of simultaneous communication is discussed in terms of its benefits for both the communicative and social competence of profoundly deaf children. (Author/MP)