The Impact of Internal Migration on Child Wellbeing study investigated the impacts of parent migration on child health and development in Thailand. The study recruited children in three distinct situations: children whose parents were alive but not usually present in the household, children who lived with their mother but whose father was absent, and children who lived with both parents. All participants were recruited from the provinces in the North and North-Eastern parts of Thailand. At baseline, over 1,000 children participated in the study and their primary caregivers or parents were also invited to provide data on the child participants.