Because of the wide range of symptoms expressed in individuals with autism spectrum disorder (ASD) and their idiosyncratic severity, it is unlikely that a single remedial approach will be universally effective. Resolution of this dilemma requires identifying subgroups within the autism spectrum, based on symptom set and severity, on an underlying neuro-structural difference, and on specific behavioral dysfunction. This will provide critical insight into the disorder and may lead to better diagnoses, and more targeted remediation in these subphenotypes of people with ASD. In this review, we discuss findings that appear to link the structure of the cerebellar vermis and plasticity of the saccadic eye-movement system in people with an autism spectrum disorder (ASD). Differences in cerebellar vermis structure in ASD could critically impact visuo-sensorimotor development in early infancy, which may in turn manifest as the visual orienting, communication and social interaction differences often seen in this population. It may be possible to distinguish a subpopulation of children with vermal hypoplasia, to establish whether this group manifests more severe deficits in visual orienting and in adaptation to persistent visual errors, and to establish whether this putative subphenotype of ASD is associated with a specific and distinct clinical symptom profile.