Health-related quality of life (HRQOL) is increasingly being considered in the management of patients with various conditions. HRQOL instruments can be broadly classified as generic or disease-specific measures. Several generic HRQOL instruments in different languages have been developed for paediatric populations including the Pediatric Quality of Life Inventory 4.0 PedsQL 4.0) Generic Core Scale. This tool and a condition-specific tool, PedsQL 3.0 Cerebral Palsy (CP) Module, are widely used in children with CP. No psychometric properties have been reported for Thai PedsQL 4.0. Therefore, this study aimed to explore the psychometric properties of the Thai version of the PedsQL 4.0 Generic Core Scales and compare these with the values for the Thai PedsQL 3.0 CP Module reported previously. Thai PedsQL 4.0 Generic Core Scales and the PedsQL 3.0 CP Module were completed, respectively, by children with CP and their parents or caregivers twice within 2-4 weeks. Respondents were 97 parents or caregivers and 54 children. Minimal missing data were found in most scales. Acceptable internal consistency was supported, except for Emotional, Social, and School Functioning. Intraclass correlation coefficients for parent-proxy report and self-report were good to excellent (0.625-0.849). The feasibility and reliability of the Thai PedsQL 4.0 Generic Core Scales were supported. The Thai PedsQL 3.0 CP Module showed higher values for the psychometric properties. Low-to-good correlations were found among the scales between the PedsQL 4.0 Generic Core Scales and the 3.0 CP Module. Both instruments could be used to measure HRQOL for children with CP, and may provide different information.