To evaluate a preventative behavioral intervention for managing early childhood caries (ECC) in a cohort of high-risk children. This pragmatic trial of the MySmileBuddy Program (MSB) evaluated preventive behavioral outcomes in a 1-y community health worker-delivered intervention to prevent ECC progression. Pre-/postintervention surveys assessed parent-reported child engagement in therapeutic toothbrushing (i.e., adult-assisted brushing with fluoridated toothpaste twice daily) and caries-related dietary behaviors and barriers. Generalized linear model with identity link for continuous variables and logit link for dichotomous outcomes evaluated pre-/postintervention comparisons and generalized estimating equations accounted for within-participant correlation (α = 0.05). Among 1,130 children with postintervention data, the average age was 3.97 y, 99% were Medicaid insured, and 88% were Hispanic. Most parents (95%) were mothers/grandmothers, married or in a committed partnership (75%), unemployed (62%), and with modest education (80% high school degree or less). The odds of reported therapeutic brushing nearly doubled (n = 864; odds ratio [OR] = 1.79, 95% confidence interval [CI] = 1.46, 2.20, P < 0.001); day and night bottle/sippy cup frequencies dropped 0.29 units (n = 871; 95% CI = -0.37, -0.33, P < 0.001) and 0.22 units (n = 1,130; 95% CI = -0.30, -0.15, P < 0.001); nighttime breastfeeding reduced 0.15 units (n = 870; 95% CI = -0.21, -0.10, P < 0.001); sharing utensils reduced 0.30 units (n = 572; 95% CI = -0.39, -0.21, P < 0.001); not using sugary foods to calm child improved 0.37 units (n = 664; 95% CI = 0.31, 0.44, P < 0.001); odds of eating meals and snacks at a table increased (n = 572; OR = 1.57, 95% CI = 1.28, 1.93, P < 0.001; n = 572; OR = 1.80, 95% CI = 1.50, 2.15, P < 0.001) respectively; and reducing barriers to behaviors improved 0.38 units for toothbrushing (n = 666; 95% CI = 0.31, 0.44, P < 0.001) and 0.33 units for diet (n = 668; 95% CI = 0.29, 0.38, P < 0.001). Despite limitations inherent to pragmatic trials, significant behavioral changes suggest that MSB yielded an important salutary impact. Forthcoming mediation analyses will explore causal pathways. Findings support integration of MSB's behavior change program in caries management initiatives. The results of this study can be used by clinicians, public health leaders, and researchers to inform the development and implementation of community-based, preventative behaviorally focused early childhood caries prevention programs. Study findings may enhance the understanding of the impact of behavioral interventions that engage parents of young children and could lead to more effective prevention for populations at high-risk of caries.