Objective To identify social and behavioral conditions that could act as risk factors to the severity of dental caries in 12-year-old children. Methods Based on the oral health survey data obtained in Florianópolis, Brazil, in 1995, social and behavior conditions were compared between two 12-year-old children groups with dental caries with different severity: high and very high severity, and very low severity. In the interview, there were questions about each family were part of the interview, besides social-economic conditions and behavior aspects. Results/Conclusions The multivariate logistic regression analysis showed that the risk factors for dental caries with high severity were candy intake and family income. Children who consumes cariogenic products 2 or 3 times a day on a daily basis has 4.41 more chance of having dental caries with high severity when compared to children who consumes these same products only once a day - CI (OR) = [1.18; 16.43]). Family income was the most important socialeconomic factor. Children whose family income is lower than five minimum wages has 4.18 more chance of having high severity dental caries when compared to children whose family income is higher than five minimum wages - CI (OR) = [1.16; 15.03]. The purpose of this study was to have a a better knowledge of dental caries occurrence in 12-year-old children who, in most cases, have a complete permanent dentition that showed the illness history.