We examined 2 hypotheses concerning the development of "audience design" by contrasting children with and without autistic spectrum disorder (ASD) in referential communication. The 2-stage hypothesis predicts that the ability to use contrastive size adjectives for ambiguity avoidance develops separately from and faster than the ability to avoid perspective-inappropriate descriptions for their addressee. The single-stage hypothesis assumes that both abilities reflect speakers' perspective-taking, and they should develop in tandem with each other. Experiment 1 found that 6- to 10-year-olds with and without ASD produced disambiguating size adjectives ("small door") equally often when the size-contrasting competitor (large door) was in the visual context "shared" with their addressee. When the competitor was hidden from their addressee, that is, it was part of children's "privileged" context, children with ASD produced more perspective-inappropriate size adjectives than those without ASD, providing support for the 2-stage model. Experiment 2 showed a similar pattern of results with 11- to 16-year-old adolescents. Compared with adults, 6- to 10-year-olds without ASD produced more perspective-inappropriate size adjectives in the privileged context, while producing fewer disambiguating size adjectives in the shared context, demonstrating more "egocentric" behaviors than adults. Importantly, whereas 11- to 16-year-olds without ASD produced disambiguating adjectives nearly as often as adults in the shared context, they produced perspective-inappropriate adjectives more than adults in the privileged context. This indicated that even in non-ASD, the ability to avoid perspective-inappropriate descriptions develops more slowly than the ability to avoid ambiguous descriptions, delaying the onset of adult-like audience design, consistent with the 2-stage hypothesis.