Aim: The aim of this study is to identify social communication skills in infancy which predict autism spectrum disorder (ASD) diagnosis by 7 years as compared with children with other developmental difficulties or typical development from within a population sample. Methods: Children with an ASD (n = 41), developmental delay (n = 28), language impairment (n = 47) and typical development (n = 41) were drawn from a large, longitudinal community sample following children from 8 months to 7 years of age, the Early Language in Victoria Study. At 7 years of age, early social communication skills at 8, 12 and 24 months from the Communication and Symbolic Behavior Scales Infant–Toddler Checklist and the MacArthur-Bates Communicative Development Inventory: Words and Gestures were compared between groups and used to predict ASD diagnosis. Results: Significant predictors of ASD diagnosis were found from 8 months, predominantly focused on gesture use and communicative behaviours, such as requesting and joint attention. While comparisons between children with ASD and children with language impairment and typical development revealed differences from 8 months of age, the developmental delay group did not differ significantly from ASD on any measure until 24 months of age. At 24 months, children with ASD had lower Communication and Symbolic Behavior Scales Use of Communication scores as compared with all other groups. Conclusions: The capacity to identify early markers of ASD should facilitate awareness of the risk of an ASD as compared with other developmental problems and point to the need for further developmental assessment, monitoring and provision of early intervention if indicated.