Asperger syndrome (AS) is a disorder of early childhood characterized by impaired social interaction, communication difficulties, play and imagination deficits and a range of routines and rituals. A review of the literature explores current issues concerning the diagnosis of AS. Despite its increasing popularity as a distinct condition, it seems to be still controversial to what extent AS differs from high-functioning autism. Especially in European perspectives, AS is a variant of autism typically occurring in high-functioning individuals, and not a separate disorder. However, the validity of AS as a different diagnostic entity has been recognized through several lines of evidence in the US. AS and nonverbal learning disabilities are often confused with some authors and practitioners not differentiating at all, others perceiving as different points along a continuum, and still others seeing them as different, albeit overlapping, disorders. The major difference is that AS is a pervasive developmental disorder, with chronically restricted repetitive and stereotyped patterns of behavior, interests, and activities, which are far beyond the narrow range of activities, social awkwardness, and slightly eccentric behaviors that are sometimes found individuals with nonverbal learning disabilities.