Objectives To evaluate the association between malocclusion characteristics in the mixed dentition stage, breastfeeding, and past nonnutritive sucking habits in school-age children. Materials and Methods A total of 547 school children in the mixed dentition, in the age range between 7 and 13 years, were evaluated by means of questionnaire and clinical examination. Binomial and multinomial logistic regression models were used to evaluate the associations between breastfeeding and finger and pacifier sucking habits, the malocclusion characteristics of posterior crossbite, and excessive or deficient overjet and overbite. Results Individuals who had nonnutritive sucking habits had 2.16 times greater chance of having anterior open bite (odds ratio [OR] 2.16; 95% confidence interval [CI], 1.07–4.33) and 2.39 times greater chance of having posterior crossbite (OR 2.39; 95% CI, 1.56–5.49). Children who were exclusively breastfed up to at least 6 months of age had a higher frequency of normality for overjet and overbite and the lowest posterior crossbite index. However, in adjusted analysis, breastfeeding showed no association with malocclusion characteristics in the mixed dentition stage. Conclusions Breastfeeding was not associated with the presence of malocclusion in the mixed dentition, whereas past nonnutritive sucking habits were associated with the occurrence of malocclusion.