Background: Early identification of Autism Spectrum Disorder (ASD) is currently limited by the absence of reliable biological markers for the disorder, as well as the reliability of screening and assessment tools for children aged between 6 and 18 months. Ongoing research has demonstrated the importance of early social communication skills in differentiating children later diagnosed with ASD from their typically developing (TD) peers, but researchers have not yet investigated whether these differences can be detected using community-ascertained systematic observation data as early as 12 months. Aims: To investigate whether differences in early social communication skills can be detected at 12 months of age, comparing children later diagnosed with ASD, and TD peers; and to determine whether differences remain when groupings are based on age of subsequent ASD diagnosis. Methods & Procedures: From a prospective community-ascertained sample, we collected data on children in early life, then conducted retrospective analyses for those children who were later diagnosed with ASD by the age of 7 years, compared with matched TD peers. We analysed standardized observational data of early communication skills, collected using the Communication and Symbolic Behavior Scales—Developmental Profile (CSBS-DP) Behavior Sample, when participants were 12 months of age. Outcomes & Results: Children in the ASD group exhibited significantly lower social communication skills than the TD group, including on the Total score and Social and Symbolic Composite scores of the CSBS-DP Behavior Sample. Differences on the Total score and Social Composite were also detected for both early and late ASD diagnosis groups when compared with the TD group. Conclusions & Implications: These findings give further support for the importance of social communication in assessing children at risk of ASD as early as 12 months of age. Future research could evaluate the sensitivity and specificity of direct observation of these early communication skills as diagnostic indicators for ASD at 12 months, and investigate whether it is possible to distinguish between ASD and other high-risk groups (e.g. developmental delay) at this age.