Background: The Children's Communication Checklist (CCC 1998) was revised in 2003 (CCC-2) to provide a general screen for communication disorder and to identify pragmatic/social interaction deficits. Two validation studies were conducted with different populations of children with language and communication impairments. Methods & Procedures: In Study 1, the questionnaire was given to families of 87 children attending full-time special education for specific language impairment, pragmatic language impairments or autistic spectrum disorders. In addition, the teachers of half the sample completed CCC-2 forms for the same children, providing evidence for interrater agreement. In Study 2, the sample was increased to include 24 children with similar diagnoses in educational contexts in Scotland and 27 children referred for clinical evaluation at a neurodevelopment centre. Outcomes & Results: The CCC-2 distinguished children with communication impairments from non-impaired peers. Furthermore, the social-interaction deviance composite (SIDC) of the CCC-2 identified children with disproportionate pragmatic and social difficulties in relation to their structural language impairments. This measure also had good interrater agreement (r=0.79). Conclusions: CCC-2 provides a useful screening measure for communication impairment and can be helpful in identifying children who should be referred for more detailed assessment of possible autistic spectrum disorder. However, the present data highlight substantial overlap amongst groups with 'distinct' diagnoses. It is suggested that it is unrealistic to use the CCC-2 to make categorical distinctions on this continuum of disorder.