Healthy default beverage laws require restaurants to list healthier beverages—such as water or unflavored milk as opposed to sugary drinks—as the default option for children's meals. These laws intend to address unhealthy beverage consumption by young children, directing consumers toward healthier beverage choices at no additional cost. New research evaluates the adherence of children's meals to healthy default beverage laws from online restaurant meal ordering platforms available in Los Angeles, Baltimore, and New York City. Among over 100 of the top-grossing restaurant chains sampled, fewer than 3% of online children meal orders in any jurisdiction adhered to the strictest interpretation of the healthy default beverage laws. Varying adherence to healthy default beverage laws by jurisdiction was found and may be attributable to differing definitions of a healthy beverage. For example, California's law considers non-flavored milk and water as healthy default beverage options, while Baltimore and New York laws also allow 100% juice and flavored milk. Policy can be optimized by clearly defining healthy beverages, bundled children's meals, and what constitutes adherence to the law for online ordering platforms. The study, published in the American Journal of Preventative Medicine, was conducted by Daniel Zaltz and Sara Benjamin-Neelson of Johns Hopkins Bloomberg School of Public Health, Danielle Lee, Gail Woodward-Lopez, and Lorrene Ritchie of the Nutrition Policy Institute, and Sara Bleich of Harvard T.H. Chan School of Public Health with partial support from a grant from the National Institutes of Health (no. T32DK062707).