The objective of the current study was to evaluate the patterns of longitudinal change in the language abilities of 28 children with autism during early and middle childhood. Results from fitting a series of multilevel models showed that children's rate of language growth was independently predicted by (a) children's responsiveness to others' bids for joint attention and (b) parents' responsiveness to their children's attention and activity during play. Both predictive relations could not be explained by initial variation in global developmental characteristics, such as IQ, mental age, or language abilities. These findings support a social?pragmatic view on language acquisition, which emphasizes the collaborative process through which children and their parents negotiate shared meaning.

Longitudinal research has demonstrated that responsive parental behaviors reliably predict subsequent language gains in children with autism spectrum disorder (ASD). To investigate the underlying causal mechanisms, we conducted a randomized clinical trial of an experimental intervention (Focused Playtime Intervention, FPI) that aims to enhance responsive parental communication (N = 70). Results showed a significant treatment effect of FPI on responsive parental behaviors. Findings also revealed a conditional effect of FPI on children’s expressive language outcomes at 12-month follow up, suggesting that children with baseline language skills below 12 months (N = 24) are most likely to benefit from FPI. Parents of children with more advanced language skills may require intervention strategies that go beyond FPI’s focus on responsive communication.