OBJECTIVES: Preference-based quality-of-life measures (PBMs) have been developed in many clinical areas to aid estimation of more accurate utility values for economic evaluations. Existing oral health-related quality-of-life (OHRQoL) instruments are non-PBM and hence, cannot be used to generate utility values. The objective of this study was to develop a classification system for a new PBM (dental caries utility index-DCUI) for the most prevalent childhood oral health condition: dental caries. METHODS: Possible domains and items to be included in the classification system were identified based on the reviewing available pediatric non-PBM OHRQoL instruments, studies eliciting utility values for oral health outcomes and clinical dentistry textbooks and based on the findings, a draft classification system was developed. To refine the draft classification system, semi-structured interviews were conducted among a convenience sample of 15 12-17-year-old adolescents who had experience with dental caries. The classification system was further refined and validated by a group of dental experts, using a modified Delphi technique. RESULTS: The classification system comprised five items (pain/discomfort, difficulty in eating food/drinking, worried, ability to participate in activities, and appearance) and each item had a four-level response scale. CONCLUSION: The classification system developed herein is considered an amenable tool for the subsequent development of a new PBM for dental caries. Once the scoring algorithm is completed, the classification system can be used to incorporate economic evaluations of dental caries health interventions.