The current study investigated whether contrasting face recognition abilities in autism and Williams syndrome could be explained by different spatial frequency biases over developmental time. Typically-developing children and groups with Williams syndrome and autism were asked to recognise faces in which low, middle and high spatial frequency bands were masked. All three groups demonstrated a gradual specialisation toward the mid-band. However, while the use of high spatial frequencies decreased in control and autism groups over development, the Williams syndrome group did not display a bias toward this band at any point. These data demonstrate that typical outcomes can be achieved through atypical developmental processes, and confirm the importance of cross-syndrome studies in the investigation of developmental disorders.