Autism Spectrum Disorders (ASD) are chronic neurodevelopmental disorders that are characterized through severe impairments of social, communicative, cognitive and language abilities. The symptomatology is heterogenous in nature and varies considerably from severe ASD with intellectual disability and delays in language development (´low functioning autism´) to ASD without intellectual and language impairments (´high-functioning autism´). As therapeutic interventions with causal effects are not known, interventions have to focus on the modification of individual symptoms. A variety of studies have stated that interventions at the earliest possible stages in the development of the child are associated with better outcomes. Therefore, the detection of early ASD symptoms, particularly through the application of screening instru¬ments is important. Yet, screening instruments for individuals with high functioning autism are rare. In the present cumulus three studies are described that explored the usefulness of screening instruments in the diagnostic assessment of children and adolescents with high functioning ASD. In study 1 a short interview was developed on the basis of an existing gold-standard diagnostic interview. The short interview showed high sensitivity and specificity for the discrimination of individuals with Asperger syndrome (AS) and attentiondeficit-/hyperactivity disorder (ADHD), especially for children and adolescents younger than 11 years. The aim of study 2 was to replicate the findings of study 1 on the basis of an independent and enlarged sample, comprising children and adolescents with high functioning ASD other than AS and children and adolescents with other psychiatric disorders. It could be shown that the short interview can be used for the detection of high functioning ASD as sensitivity was sufficient, yet specificity was low. Therefore, discrimination of ASD and other psychiatric disorders was difficult. Study 3 examined if a questionnaire that was originally designed for the identification of problem behavior in children and adolescents can be used as screening instrument for ASD. The results show a high prevalence of accompanying emotional and behavior problems in children and adolescents with ASD. Furthermore, the evaluated questionnaire is not a suitable screening instrument for the identification of ASD, but it can be used for the assessment of co-occurring behavior problems.