This dataset, in combination with third-party data, was used to estimate the impact of the COVID-19 pandemic on the cognitive, language, and motor development, behavior, and growth among toddlers in rural Bangladesh. The study compared repeated cross-sectional surveys of children living in the same villages. The first survey (third party data) included 20-month-old children in 2019 and 2020 (unexposed group). The second survey (this dataset) took place in a random subset of 50 of the same villages in 2022 among 20-month-old children, who had experienced pandemic-related lockdowns from approximately mid-gestation through their first year (exposed group). Both surveys used similar inclusion criteria and the same developmental assessments (Bayley’s Scales of Infant and Toddler Development), behavior observations, and field protocols.