Although we have the knowledge and technology necessary to prevent it, most children experience dental disease, and a few children continue to experience high rates of decay. The appropriateness and effectiveness of preventive measures vary throughout the life of a child, and recommendations should be tailored to the needs of the individual. Water fluoridation continues to be the most cost-effective preventive measure available. For patients who do not have access to fluoridated water, dietary supplementation offers similar benefits. A wide variety of professionally applied and home use topical fluoride products such as dentrifrices, gels, and rinses can also reduce the risk of dental caries, particularly on the smooth surfaces of the teeth. The most common site of decay in children is the fissures of the molar teeth. These areas can be protected by the professional application of plastic sealants. Dietary practices influence caries rates, and patients should be advised to limit the frequency of carbohydrate exposures rather than the total amount of carbohydrates consumed. Parents of infants should be advised to discontinue bottle feeding around the age of 12 months to avoid nursing caries. Although oral hygiene practices are not as effective in reducing caries rates as is generally believed, daily toothbrushing and flossing are unquestionably effective in preventing periodontal disease. In order to be maximally effective, preventive efforts should be initiated early in the life of the child. Although most children experience dental disease, a mouth free of caries and periodontal disease is a potentially attainable goal for all children when they use currently available techniques.