Autism is a lifelong handicapping disorder that occurs on a continuum of severity. Children who show mild autistic behaviors but do not meet the criteria for a diagnosis of autism are often called autistic-like, but it is not known if their development and functioning are similar to that of autistic children. A follow-up study was done on 35 autistic and autistic-like children who were an average of 3 years of age when initially seen. Initial test scores indicated that the children were similar on measures of intellectual/developmental functioning, receptive vocabulary, and adaptive functioning. Approximately 4 years later they were evaluated again. Using the Childhood Autism Rating Scale, the children were divided at follow-up into three groups: nonautistic, mildly/moderately autistic, and severely autistic. Most children made gains on intelligence tests and displayed a diminishing number of autistic symptoms. Changes in nonverbal intelligence, adaptive functioning and receptive vocabulary scores depended on group membership. The results are discussed in relation to the reported stability of cognitive functioning in young autistic children and the implications for clinical practice, early intervention, and research on attachment. The nature of the syndrome of autism is also discussed, particularly in its relation to the milder, atypical children. The …