Childhood obesity is a multifactorial disease, shaped by child, familial, and societal influences; prevention efforts must begin early in childhood. Viewing the problem of childhood obesity through a developmental lens is critical to understanding the nuances of a child's interactions with food and their environment across the span of growth and development. Risk factors for childhood obesity begin prior to birth, compounding across the life course. Some significant risk factors are unmodifiable (e.g., genetics) while others are theoretically modifiable. Social inequities, however, hinder many families from easily making modifications to a range of risk factors. The objective of this review is to provide background and an overview of the literature on childhood obesity in early childhood (birth to 5 years of age) in a developmental context. Special focus is placed on unique developmental considerations, child eating behaviors, and parental feeding behaviors in infancy, toddlerhood, and preschool ages. Expected final online publication date for the Annual Review of Developmental Psychology, Volume 3 is December 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.