Little empirical evidence exists about school-age pragmatic communication or predictors in siblings at heightened familial risk for ASD (HR) and low-risk (LR) controls. The Pragmatic Rating Scale-School-Age (Landa unpublished) was scored for 49 HR siblings and 18 LR controls at 8-12 years. Social-communication and language measures were collected between 14 and 36 months. At 36-months, siblings were classified as ASD (HR-ASD, n = 15), broad autism phenotype (HR-BAP, n = 19), or typically developing (HR-TD, n = 15). Results revealed a pragmatic continuum with significantly better scores for HR-TD than HR-BAP or HR-ASD, and HR-BAP than HR-ASD. Per regression models including all participants, 14-month joint attention initiations predicted school-age pragmatic communication, as did 24-month social-communication and expressive language scores. Early joint attention, social-communication, and language abilities contribute to later pragmatic functioning.