Purpose: To assess the role of sociodemographic, dietary, and clinical factors in early mutans streptococci (MS) colonization in children aged 6 to 24 months who were followed for 18 months. Materials and Methods: Ninety-four children (mean age: 11.5 ± 4.99 months at baseline) were enrolled in the study from the Women, Infants and Children Supplemental Nutrition Program during 2003-2004. Salivary MS levels of the children were determined at baseline and at 18 months using a semi-quantitative method. Detailed information about the children's beverage consumption pattern, dietary behavior, and clinical information about oral health status was collected at baseline, 9 months, and 18 months. None of the children included in this study had detectable levels of MS at baseline. Results: Of the 94 children at baseline, 36 (38%) had acquired MS by the 18-month follow-up. The presence of >5 teeth [OR = 3.55 (1.46-9.04); p = 0.0062] was a significant risk factor for MS acquisition among the baseline variables. At 9 months, sports drinks consumption [OR = 5.56 (1.39-26.26); p = 0.0143] and presence of caries [OR = 9.36 (2.55-40.90); p 0.0001] were significantly associated with MS colonization at 18 months. Higher maternal education [OR = 0.3 (0.07-1.36); p = 0.0351] was a protective factor at all the time points. Conclusion: Sugared beverage consumption, tooth-related factors, and lower maternal education can predict MS acquisition in young children. Parole chiave: behavior, children, diet, factors, mutans streptococci, WIC