Background: Caries in Peruvian 0- through 3-year-olds is high. The dental profession should collaborate with nurses at mother and child health (MCH) clinics for reducing the disease. In this randomized clinical trial, the authors tested an integrated intervention program implemented by nurses and dentists. Methods: The authors developed age-specific (0-3 years) oral health–related information and activity record cards and validated them for nurses to use after being educated about oral health issues and mouth inspection. The authors trained dentists in atraumatic restorative treatment. The active intervention group (AG) participated in the integrated intervention program, the passive intervention group (PG) received only the oral health–related information and activity record cards, and the control group (CG) received only a lecture. The examiners assessed caries status according to the Caries Assessment Spectrum and Treatment instrument. The authors used analysis of variance and the Tamhane method to analyze the data. Results: The sample consisted of 368 children with a mean age of 3.1 years. The 3-year dropout percentage was 40.5%. The prevalence of cavitated dentin carious lesions was statistically significantly lower in the AG (10.0%, confidence interval [CI] 4.1 to 19.5) than in the PG (60.5%, CI 48.6 to 71.5) and CG (63.0%, CI 50.9 to 74.0) after 3 years (P < .001). Enamel carious lesions (62.9%) were most prevalent in the AG, whereas carious lesions were most prevalent in the PG (28.9%) and CG (32.9%). Conclusions: Incorporation of specific oral health care activities into the existing MCH program, implemented by trained nurses and supported by health center dentists, reduced the burden of caries in 3-year-olds substantially. Practical Implications: The oral health care professionals in Peru should collaborate with personnel of MCH clinics to curb caries in 0- through 3-year-olds.