The development of appropriate social skills is critical for all children in establishing relationships and being able to successfully participate in their communities. Children with Autism Spectrum Disorder (ASD), however, have pronounced difficulties with social skill acquisition, development, execution, generalization and maintenance, which are characteristic of the disorder. For children with ASD, the development of fundamental social skills (e.g., saying thank you, smiling when seeing their caregiver) to more complex social skills (e.g., expressing empathy and cooperation) represent unique challenges. Yet, little research has focused on complex social skills as an outcome of Early Intensive Behavioural Intervention (EIBI), a well-established intervention for children with ASD. The present study evaluated fundamental and complex social skills in a sample of 16 children with ASD from two community settings in Québec before and two years after participating in EIBI. Pre-intervention and post-intervention measures included the Social Skills Improvement System (SSIS) to screen for complex social skills and problem behaviours, and the Adaptive Behavior Assessment System (ABAS-II) to screen for fundamental social skills. Significant pre- to post-test improvements in social skills were found with the ABAS-II but not with the SSIS. Although preliminary, these findings are suggestive that within EIBI programs, specific social skills should be targeted directly.