This paper describes a highly structured assessment protocol with objective behavioral measures for joint attention responding and initiation. The assessment was given to 26 children diagnosed with autism spectrum disorders and 21 typically developing children, aged two to four years. Interobserver agreement was high for all behavioral measures. Children with autism had relatively minor deficits in joint attention responding and more severe deficits in joint attention initiation, relative to typically developing children. These results replicate those reported in previous research. The protocol can be used reliably to assess behavior indicative of joint attention responding and initiation in typically developing children and children with autism.