Background <p>The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) infant food packages contain up to 13,071 mL/month of infant formula for infants ages ≤12 months. Because remote WIC services led to a telephone-based breastfeeding assessment and a new management information system (MIS) in 2020 that modified infant food package options, this study aimed to determine whether the WIC infant food package data remain a reliable proxy for infant feeding practices.</p> Methods <p>A prospective cohort study of prenatal respondents to the 2020 Los Angeles County WIC Survey (<i>n</i> = 358). Survey-assessed and administrative infant food package data were categorized for breastfeeding status (formula feeding, mixed feeding, fully breastfeeding) at three and 10 months postpartum. Agreement of maternally-reported and WIC infant food package data was assessed for breastfeeding status, at three and 10 months postpartum, with percent agreement and Kappa coefficients and for breastfeeding duration with intraclass correlation coefficients.</p> Results <p>Agreement was substantial for breastfeeding status at three and 10 months postpartum (weighted Kappas of 0.77 and 0.71, respectively) and moderate for breastfeeding duration (intraclass correlation coefficient 0.74).</p> Conclusions <p>WIC infant food package data remain a reliable proxy of infant feeding for&#xa0;research following the introduction of remote services and a new MIS.</p> Impact <p><UnorderedList Mark="Bullet"> <ItemContent> <p>WIC infant food package data are a reliable proxy for breastfeeding status</p> </ItemContent> <ItemContent> <p>WIC infant food package data are a reliable proxy for breastfeeding duration</p> </ItemContent> <ItemContent> <p>WIC infant food package data can be used for population surveillance of breastfeeding practices</p> </ItemContent> </UnorderedList></p>