To estimate the impact of recent changes to the Child and Adult Care Food Program (CACFP) meal pattern on young children's diets in family child care homes (FCCHs) serving racially/ethnically diverse children. In a natural experimental study of thirteen CACFP-participating FCCHs, we used digital photographs taken of children's plates before and after meals matched with menus to measure children's dietary intake both prior to implementation of the new meal patterns (summer/fall of 2017) and again 1 year later (summer/fall of 2018). Generalised estimating equations tested for change in intake of fruits, vegetables, whole grains, 100 % juice, grain-based desserts, meat/meat alternates and milk, adjusting for clustering of observations within providers. FCCHs in Boston, MA, USA. Three- to 5-year-old children attending FCCHs. We observed 107 meals consumed by twenty-eight children at the thirteen FCCHs across an average of 2·5 (sd 1·3) d before the CACFP policy change, and 239 meals consumed by thirty-nine children across 3·8 d (sd 1·4) 1 year later. During lunch, fruit intake increased by about a third of a serving (+0·38 serving, 95 % CI 0·04, 0·73, P = 0·03), and whole grain intake increased by a half serving (+0·50 serving, 95 % CI 0·19, 0·82, P = 0·002). No changes were seen in other meal components. Young children's dietary intake in CACFP-participating FCCHs improved following the CACFP meal pattern change, particularly for fruits and whole grains, which were targets of the new policy. Additional research should examine impacts of the changes in other child care settings, age groups and locales.