BACKGROUND: Cerebral palsy (CP) often presents alongside cognitive developmental delays and motor impairments. This study aimed to identify the function most closely linked to the development of fluid intelligence in individuals with CP, and to estimate the point at which the fluid intelligence of children with CP diverges from that of typically developing (TD) children. METHODS AND PROCEDURES: Raven's Coloured Progressive Matrices (RCPM) were used to evaluate the fluid intelligence of participants. Fifty-one participants with CP aged 4-18 years and 33 TD children aged 3-9 years were included in this study and underwent RCPM testing. The severity of CP was assessed using the Gross Motor Function Classification System (GMFCS), Manual Ability Classification System (MACS) and Communication Function Classification System (CFCS). RESULTS: Multiple regression analysis demonstrated that within the three distinct functional levels, MACS was a significant predictor of fluid intelligence in children with CP (β = - 0.29, p <
0.05). Significant disparities in the development of fluid intelligence between the CP and TD groups emerge after 57.6 months of age. CONCLUSIONS AND IMPLICATIONS: The findings offer valuable insights into timely and functionally targeted interventions to prevent cognitive stagnation.