Purpose: This study attempts to describe the caries experience in 12-year-old schoolchildren in Piracicaba, Brazil, and to verify the relationship between the disease and socioeconomic factors, and behavioural variables related to oral health. Materials and Methods: The random sample consisted of 939 individuals from public and private schools in Piracicaba, São Paulo State, Brazil, in 2005. A calibrated dentist performed the examination in an outdoor setting, under natural light, using CPI probes and mirrors, following WHO recommendations. A questionnaire was sent to the parents to collect information on socioeconomic level and behavioural variables related to dental health. The mean number of decayed, missing and filled permanent teeth and surfaces (DMFT/DMFS), the Care Index and the SiC (Significant Caries Index) were determined. Multiple logistic regression analyses using the stepwise procedure were performed in order to identify the risk indicators for the DMFT and for the polarisation group. Results: The DMFT and the SiC Index were 1.32 (SD = 1.92) and 3.52 (SD = 1.86), respectively, and the Care Index was 75.0%. The regression models showed that females and children with either low family income or low education level of the fathers were prone to have caries or take part in the polarisation group. Conclusion: The 12-year-old individuals from Piracicaba presented a low prevalence of caries. Nevertheless, those high carieslevel individuals showed moderate caries experience. The socioeconomic and the behavioural variables related to dental health were risk indicators of caries in permanent dentition not only for the entire sample, but also for the polarisation group. Keywords: dental caries, epidemiology, schoolchildren