Caries in China appears to be a significant problem, especially among preschool children. The effect of caries prevention in the primary teeth of preschool children through the use of fluoridated dentifrices and prevention programs has not been widely addressed. The purpose of this study was to examine the caries preventive effects of an 1100 ppm sodium fluoride dentifrice used in the context of a kindergarten-based oral health program compared to a matched placebo dentifrice in the absence of a kindergarten-based oral health program. This was a randomized, placebo-controlled, examiner-blind, two-year caries study. A population of 1,334 preschool school children, three years of age, was recruited from 24 school kindergartens in Huairoi and Miyun counties, located approximately 60 kilometers northeast of Beijing, China. Classrooms were stratified based on mean baseline dmfs scores derived from the visual-tactile baseline examination, and randomly assigned to one of the two dentifrice treatment groups: 0.243% sodium fluoride (1100 ppm fluoride ion) or placebo (0 ppm fluoride ion). Children attending the schools participating in the program brushed twice a day (morning and afternoon) at school under the supervision of classroom teachers during the school week. The children randomized to schools receiving the placebo dentifrice were supplied with toothbrushes and dentifrice for ad libitum use at home and did not participate in the school program or supervised classroom brushing. For the primary examiner, the two-year caries increment data demonstrated evidence of anticaries efficacy for the sodium fluoride dentifrice/school program group as compared to the placebo/no school program group. In the evaluable subset, the 1100 ppm fluoride treatment group had a 20.7% reduction in dmfs compared to the placebo treatment group, that was statistically significant (p = 0.004). The secondary examiner observed a similar overall treatment effect, as the 1100 ppm fluoride treatment group had an 22.1% reduction in dmfs compared to the placebo treatment group that was statistically significant (p = 0.014). In contrast to the primary examiner, there was a county-by-treatment interaction for the secondary examiner's results necessitating that the counties be examined independently. In Miyun county, the sodium fluoride/school program group had a 39.9% reduction in caries compared to the placebo/no program group that was statistically significant (p = 0.001). In Huairou county, the sodium fluoride/school program group had a 6.8% reduction in caries compared to the placebo/no program group that was not statistically significant (p > 0.05). These results demonstrate that fluoride in conjunction with increased dental awareness can deliver important reductions in caries in preschool children.