The clinical behavior of future adhesives and composite materials for dental restorations will be significantly improved from the performance of today's restorative materials. The adhesives and composites available to the practicing dentists in 10 years will be designed and developed as preventive resin restorations. They will consist largely of adhesive-sealant and composite resin combinations. The new restorations will be developed in response to early detection of caries, resulting in smaller lesions, and smaller restored surfaces exposed to the oral cavity. There will be less margin length, less vulnerability to wear, and less microleakage. The materials of the 21st century will be less technique sensitive in the hands of the clinician and therefore will result in fewer clinical failures. The advent of better wetting and better bonding adhesives to both enamel and dentin, combined with nonshrinking dental resins that are durable, esthetic, and biocompatible, will significantly improve available dental health care. The clinical behavior of these 21st century materials should provide longer wearing, nonleaking, esthetic restorations that are easily manipulated and placed by clinicians at an economical cost to dental patients.