BackgroundThis paper describes the design and methods of a multi-phase study to reduce early childhood caries and obesity in vulnerable South Asian (SA) immigrants in the United States. Early childhood caries and obesity are the most common diseases of early childhood. Risk factors for both diseases are rooted in early childhood feeding practices such as bottle feeding and intake of sweets and sweetened beverages. The Common Health/Risk Factor Approach to addressing oral health is widely promoted by the WHO and other policy makers. This approach recognizes links between oral health and other diseases of modernity. Our CHALO! (“Child Health Action to Lower Obesity and Oral health risk”--from a Hindi word meaning "Let's go!") study targets SA families at high risk for early childhood caries and obesity. CHALO! addresses common risk factors associated with these two common diseases of childhood.MethodsThis two part project includes a randomized controlled trial, and a Knowledge Translation campaign. A randomized controlled trial will enroll n = 360 families from pediatric practices serving South Asians in the New York metro area. The intervention group will receive home visits by SA community health workers at 6, 8, 10, 12, 14, and 16 months of age. Controls will receive culturally tailored educational material. Primary outcomes-- cariogenic and obesogenic feeding practices at 6, 12, and 18 months-- will be assessed with the MySmileBuddy iPad based tool. Secondary outcomes include: oral hygiene practices, anthropometrics, and caries incidence at 18 months. A public education campaign will focus on both families and health care providers.DiscussionThere are few Common Health/Risk Factor Approach published studies on obesity and oral health risk in children, despite health morbidity and costs associated with both conditions. CHALO! comprises a multi-level interventions designed to promote culturally competent, sustainable change.Trial registrationClinicalTrials.govNCT03077425.