Forty-three percent of children younger than 5 years in low- and middle-income countries (LMICs) are at risk of not meeting their developmental potential. This study investigated how 3 aspects of national development (national life expectancy, education, and income levels) are associated with early childhood development by influencing 5 domains of nurturing care (caregiving, the learning environment, safety and security, nutrition, and the health of the home environment). In total, 159,959 families with children aged 36 to 59 months living in 51 LMICs provided data. National development was measured using 3 indicators (national life expectancy, education, and income levels), and nurturing care was measured using 10 indicators that collectively captured the 5 nurturing care domains. Path analyses examined how nurturing care indicators mediated the effects of national development on early childhood development. Higher national life expectancy was directly associated with more advanced childhood development. Higher national levels of education and income were indirectly associated with more advanced childhood development through aspects of nurturing care, such as reduced caregiver psychological aggression or physical violence, increased learning materials and wired appliances in the home environment, and greater caregiver education and child height-for-age. Greater caregiver cognitive caregiving practices promoted childhood development, regardless of levels of national development. Intervening to promote caregiver education, appropriate discipline strategies, cognitive caregiving practices, and family access to wired appliances, learning materials, and adequate nutrition is key to promoting childhood development in nations with lower levels of national development.