Aim: To examine psychometric properties and clinical utility of the Functional Communication Classification System (FCCS) for classifying observable communication function in children with cerebral palsy (CP) aged 5 to 18 years.

Method: Eighty‐two children (38 males, 44 females) with CP in six age groups (5y [n=15], 8y [n=14], 10y [n=14], 12y [n=14], 15y [n=11], and 17y [n=14]) were assessed by a speech‐language pathologist (SLP) and parent for FCCS ratings. Data were compared with: (1) everyday communication function, assessed using the Clinical Evaluation of Language Fundamentals – Fourth Edition Pragmatics Profile (CELF‐4 PP) for familiar and unfamiliar partners; (2) motor speech, gross and fine motor function; and (3) associated impairments, including epilepsy, intelligence, hearing, and vision. Interrater agreement was calculated for FCCS ratings using kappa (κ) statistics. Relationships between FCCS ratings and other measures were examined using Spearman's correlation coefficient.

Results: Almost perfect interrater agreement was demonstrated between SLP and parent FCCS ratings (κw=0.96). Correlations were excellent between FCCS ratings with CELF‐4 PP ratings, motor speech, and intellect; moderate with gross and fine motor function; and fair with other associated impairments (hearing, visual, and epilepsy). There was no correlation between age and FCCS.