The current study investigated clinicians' perspectives on the effectiveness of interventions designed to support the development of children with autistic spectrum disorders (ASDs). Researchers developed a semi-structured interview which was administered to 11 clinicians involved in the assessment and treatment of ASDs (5 = clinical psychologists, 6 = psychiatrists). Content analysis of qualitative data revealed that Irish clinicians typically endorse an eclectic approach to treatment, combining facets of different methods of interventions in a complementary fashion. The process that clinicians engaged in when evaluating modes of treatment was assessed. Significant variation was observed in how clinicians merge clinical experience with empirical evidence. Challenges which clinicians face in assessing individuals on the autistic spectrum, such as the proliferation of misinformation on interventions, as well as the role of parents in treatment, were also discussed within the interviews. The implications of the findings for understanding the process of selecting interventions for children with ASDs are discussed. (Contains 2 figures.)