The Manual Ability Classification System (MACS) is a newly developed five-level classification that describes how children with cerebral palsy (CP) use their hands when handling objects in daily life. Since the MACS level is to be determined by asking the parents or someone else who knows the child well, it is important that the classification is meaningful and easy to understand. The aim of this study was to investigate the content validity based on parents' and therapists' descriptions of the children's ability to use their hands in daily manual tasks. Twenty-five children were represented by a parent and a therapist. After a short presentation of MACS, the respondents rated the child's MACS level. Subsequently, in a short interview, they described their thoughts about the child's ability, the classification, and the scoring process. Parents and therapists found that MACS gives a good description of how children with CP use their hands in daily activities. They found the differences between the five levels meaningful and generally easy to determine. A unique description of the children's ability at each level confirmed the validity. This provided evidence which strengthened the content validity of MACS in a descriptive way. Additional information complementing the existing leaflet could facilitate the scoring process.