To explore the different developmental trajectories of social-communicative skills in children with autism and typically developing infants, two longitudinal studies were conducted. In Study 1, we examined the developmental sequence of social-communicative skills in 26 typically developing infants when they were 9 months old and reexamined them when they were 12 and 15 months old. The results indicated a reliable developmental sequence of social-communicative skills in infants with typical development. In Study 2, we explored the emergence sequence of social-communicative skills of 23 children with autism and 23 children with developmental delay between the ages of 2 and 4 years. The results demonstrated that the developmental sequence of social-communicative skills in young children with autism and children with developmental delays was different.