Abstract Purpose An efficient and reliable way to categorize children's communication impairments based on routine clinical assessments is needed to inform research and clinical decisions. This preliminary study assessed interrater reliability of speech-language pathologists' categorization of preschoolers' speech, language, and communication impairments using a clinical consensus document. Method Six speech-language pathologists at three community sites worked in pairs to assess 38 children aged 1–5 years, then used the clinical consensus document to categorize children's communication impairments broadly. Identified language and speech sound impairments were further subcategorized. Results Speech-language pathologists had substantial to almost perfect agreement for three broadly focused impairment categories. Agreement for whether language difficulties/disorders were developmental or associated with a biomedical condition was almost perfect, but moderate for whether difficulties impacted receptive or expressive language, or social communication skills. Agreement was fair for rule-based speech delays/disorders, but low for motor-based and mixed speech impairments. Conclusions Results support use of the clinical consensus document to collect data for reliable categories. Additional work is needed to confirm reliability for some broadly focused impairment categories and for subcategorization of speech impairments.