The Autism Genome Project (AGP) is a large-scale, collaborative genetics research project that aims to identify autism susceptibility genes. The genetic architecture of autism is undoubtedly complex. This means that the identification of autism risk factors requires large samples of well characterised individuals, and strong scientific cooperation between clinical and laboratory researchers. The AGP consortium was initiated to pool resources, and clinical and scientific expertise. The clinicians and scientists participating in the AGP embody the phenotypic, statistical, molecular, and functional expertise needed to define the genetic architecture of autism.