Coded home videotapes of 11 autistic and 11 normally developing children's first year birthday parties for social, affective, joint attention, and communicative behaviors and for specific autistic symptoms. Autistic children displayed significantly fewer social and joint attention behaviors and significantly more autistic symptoms. In combination, four behaviors correctly classified 10 of 11 autistic children and 10 of 11 normal children. These behaviors consisted of pointing, showing objects, looking at others, and orienting to name.