This study examined the relationship between early intersubjective skills (joint attention and affect sharing) and the development of the understanding of intentionality in 16 young children with Down syndrome (DS) and 16 developmentally matched children with other developmental disabilities (DD). The study of intentionality focuses on how children come to understand the goal-directed actions of others and is an important precursor to the development of more complex social cognitive skills, such as theory of mind. Joint attention and affect sharing were examined using the Early Social Communication Scales (Mundy, Sigman, & Kasari, 1990; Seibert, Hogan, & Mundy, 1982). Meltzoff's (1995) behavioral reenactment paradigm was used to examine the understanding of intentionality. For children with DS, higher rates of affect sharing were associated with poorer intention reading abilities. This pattern was not observed in children with other DD. These results suggest that the intersubjective strengths associated with DS may not support the development of intentionality-interpretation skills. Future research is needed to explore if children with DS have the joint attention behaviors needed to be intentional.