The extent to which early social communication behaviors predict later communication and intellectual outcomes was investigated via retrospective video analysis. Joint attention, imitation, and complex object play behaviors were coded from edited home videos featuring scenes of 29 children with ASD at 9–12 and/or 15–18 months. A quantitative interval recording of behavior and a qualitative rating of the developmental level were applied. Social communication behaviors increased between 9–12 and 15–18 months. Their mean level during infancy, but not the rate of change, predicted both Vineland Communication scores and intellectual functioning at 3–7 years. The two methods of measurement yielded similar results. Thus, early social communicative behaviors may play pivotal roles in the development of subsequent communication and intellectual functioning.