or autistic spectrum disorder (Sparrow, 1997):

1. Multiple areas of functioning must typically be assessed, including current intellectual and communicative skills, behavioral presentation, and functional adjustment.

2. A developmental perspective is critical. Given the strong association of mental retardation with autism, it is important to view results within the context of overall developmental level.

3. Variability of skills is typical, so it is important to identify a child’s specific profile of strengths and weaknesses rather than simply present an overall global score. Similarly, it is important not to generalize from an isolated or “splinter” skill to an overall impression of general level of ability, since such skills may grossly misrepresent a child’s more typical abilities.

4. Variability of behavior across settings is typical. Behavior of a child will vary depending on such aspects of the setting as novelty, degree of structure provided, and complexity of the environment; in this regard, observation of facilitating and detrimental environments is helpful.

5. Functional adjustment must be assessed. Results of specific assessments obtained in more highly structured situations must be viewed in the broader context of a child’s daily and more typical levels of functioning and response to real-life demands. The child’s adaptive behavior (i.e., capacities to translate skills into real world settings) is particularly important.

6. Social dysfunction is perhaps the most central defining feature of autism and related conditions, so it is critical that the effect of a child’s social disability on behavior be considered.

7. Behavioral difficulties also must be considered, since they affect both the child’s daily functioning and considerations for intervention.

Various diagnostic instruments can be used to help structure and quantify clinical observations. Information can be obtained through observation (e.g., the Autism Diagnostic Observation Scale, Lord et al., 2000) as well as the use of various diagnostic interviews and checklists, e.g., Autism Diagnostic Interview-Revised (Lord et al. 1994); Childhood Autism Rating Scale (Schopler et al., 1980); Autism Behavior Checklist (Krug et al., 1980); Aberrant Behavior Checklist (Aman and Singh, 1986). An adequate assessment will involve both direct observation and interviews of parents and teachers.

The range of syndrome expression in autism and autistic spectrum disorders is quite broad and spans the entire range of IQ (Volkmar et al., 1997). A diagnosis of autism or autistic spectrum disorder can be made in a child with severe or profound mental retardation as well as in a child