Three groups of children with communication disorders were assessed using the CELF (Clinical Evaluation of Language Fundamentals). The results were used to compare the language skills of children with specific language impairment (SLI), autistic spectrum disorder (ASD) and a middle group who shared some characteristics of both SLI and ASD (Shared group). The children were aged between 5 years 10 months and 10 years 7 months. Each child was assessed on either the CELF UK 3 or the CELF Preschool, depending on their age and ability. The overall language profiles were compared and differences were found between the three groups. A more detailed analysis of the individual subtests was made, which showed that all three groups had the least difficulty with "Listening to Paragraphs" (which involves abstracting and remembering information from two short texts). It also showed that all three groups had difficulty with "Recalling Sentences" (which involves repeating sentences of increasing length and complexity). This paper discusses the value of using a more comprehensive range of linguistic assessments when considering the similarities and differences between groups of children within this population, it also considers the educational and clinical implications and makes suggestions for future research.