The aim of this study was to evaluate the impact of oral conditions on functional limitations among preschoolers. A preschool-based, cross-sectional study was carried out with 843 preschoolers in Campina Grande, Brazil. Parents/caregivers answered a questionnaire addressing socio-demographic characteristics and perceptions regarding the general/oral health of their children as well as the Brazilian version of the Early Childhood Oral Health Impact Scale. The nonparametric Kruskal-Wallis test followed by Mann-Whitney test (α = 5%) was used to compare mean children's quality-of-life scores for each independent variable. Poisson regression analysis was used to test associations between the independent and dependent variables (difficulties eating, drinking and speaking) (α = 5%). The multivariate regression model involved a hierarchical approach with four levels (distal to proximal determinants): (i) socio-demographic aspects; (ii) health perceptions; (iii) oral conditions; and (iv) pain conditions. The prevalence of negative impact on function was 24.7% for eating/drinking and 8.0% for speaking. Significant associations were found between toothache and negative impact on eating/drinking (PR = 5.38; 95%CI: 3.20-9.02) as well as between high severity dental caries and negative impact on speaking (PR = 14.91; 95%CI: 1.98-112.32). Dental caries, traumatic dental injury and malocclusion were not significantly associated with a negative impact on eating or drinking. However, toothache was an indicator of negative impact on eating/drinking and dental caries severity was an indicator of negative impact on speaking.