In December 2011, San Francisco enacted the first citywide ordinance–the Healthy Food Incentives Ordinance– prohibiting restaurants in the city from giving away free toys or other incentives with children’s meals or with foods and beverages not meeting minimal nutritional criteria. This paper examines the impact of the ordinance on restaurant response (e.g., toy-distribution practices, changes in children’s menus) and child food and beverage orders in a natural experiment at two global fast food restaurant chains operating in San Francisco before and after ordinance enactment. Researchers found that both restaurant chains used the compliance strategy of offering toys for an additional 10 cents with the purchase of a children’s meal, and neither changed their menus to meet ordinance-specific nutritional criteria. Among children for whom children’s meals were purchased, significant decreases in calories, sodium, and fat per order were found over time at Chain A. These decreases were likely due to changes in children’s default side dishes and beverage options at Chain A which were not directly in response to the ordinance but were in directions consistent with the ordinance intent. Study results support the concept that more healthful defaults may be a powerful and rapid approach for improving dietary intakes.