In order to evaluate evidence for the social-cognitive theory of joint attention, we examined relations between initiation of and response to joint attention at 12 and 18 months of age and pragmatic and structural language approximately 6 years later among children with and without autism spectrum disorder. Initiation of joint attention at 18 months was associated with structural, "but not pragmatic," language for children with and without autism spectrum disorder. School-age children with autism exhibited difficulties with structural and pragmatic language relative to non-autistic siblings of children with autism and low-risk controls. No evidence of the broader autism phenotype was observed. These findings do not support the social-cognitive theory of joint attention.