Bottle-fed infants are at greater risk for overfeeding and rapid weight gain (RWG), so evidence-based strategies for promoting healthy bottle-feeding practices are needed. The aim of this study was to assess whether policy, systems, and environmental (PSE) strategies for promoting responsive bottle-feeding practices within the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) were associated with lower risk for RWG. In a randomized trial, PSE strategies were implemented at 3 WIC clinics in Los Angeles County. PSE clinics were compared with 3 matched control clinics. Infants in WIC clinics wherein PSE strategies were implemented had 64% lower likelihood of exhibiting rapid weight gain compared with infants in control clinics. Prevalence of exclusive and any breastfeeding was similar for mothers in the PSE and control clinics, suggesting the PSE strategies did not negatively affect breastfeeding support.