Twenty years ago the caries prevalence in Swedish children was among the highest in the world; within Sweden, it was highest in the County of Värmland. Ongoing clinical research projects were initiated to evaluate the separate and combined effects of preventive measures, and in 1978 a preventive program, based on caries risk assessment, was introduced for 3- to 19-year-olds in the county. The effects were monitored by a computerized epidemiological system. From 1979 to 1991, caries prevalence and incidence decreased by 75–90 and 75–85%, respectively. The percentage of caries-free 3-year-old children increased from 51 to 94%, and in 12-year-old children, the caries prevalence decreased from 6.5 to 1.0 DFS, the lowest in Sweden. The program is very cost-effective, and in 1990 the mean annual treatment time per child was the lowest in Sweden. Currently, new methods of caries risk prediction and integrated caries prevention are being developed, with special reference to cost-effectiveness.