For preverbal children, episodes of joint attention are contexts for communication with responsive adults. This study describes the joint attention of 3- to 5-year-old children, 15 with autistic disorder (AD) and 15 with developmental language disorder (DLD), during play sessions with unfamiliar adults. Adults used fewer conventional than literal bids for joint attention with AD children and vice versa with DLD children. Children with AD were less likely to engage in joint attention than children with DLD. In the allocation of attention, AD children monitored the channel of communication with the adult 37% less often than DLD children. We discuss how perturbations in reciprocal interactions permeate the sharing situation and the implications of this problem for the mastery of cultural conventions.