The present study aims at determining a reliable screening test for the prediction of caries. In order to identify children at risk of caries, individual classifications were recorded for 268 children at the age of 7 years, according to different screening criteria of the caries experience in the deciduous dentition and according to caries increment as validation criterion. In order to determine the best screening criterion, ratios of sensitivity, specificity and false-positive and false-negative ratios were computed and plotted in receiver operating characteristic curves. The best screening criterion at less than or equal to 4 dmft resulted in a sensitivity ratio of 0.69, specificity of 0.72 and diagnostic power of 0.78 for caries increment in the permanent dentition at the age of 7-11 years. The potential of the screening is elucidated with an example, showing that 48% of the expenses needed for a preventive treatment for all children could be saved by selecting children at risk with the aid of a screening test. The disadvantage of this decision making is that 19% of the children who develop caries would not benefit from the preventive treatment.