THE GENERAL effectiveness of fluoridated water in reducing the incidence of tooth decay in children is exhaustively documented and well accepted. However, many communities do not have fluoride in their water and they must, therefore, seek some other supplementation such as fluoride tablets or fluoride in a vitamin preparation. To our knowledge, there is only one published study on the clinical effectiveness of a supplementary vitamin-fluoride preparation as an anticariogenic agent.1The results of this study seemed to indicate that a vitamin-fluoride preparation was an effective substitute for fluoridated water. In 1960 we became concerned with the following questions: (1) Would single daily doses of fluoride give clinical effects comparable to the small frequent amounts received through water intake? (2) How would caries rates in children started on fluoride at birth compare with those of children started at age 4? (3) Is it therapeutically desirable to give daily measured