There is almost universal consensus regarding the high importance and desirability of positive well‐being in children. Despite this consensus, the study of children has traditionally focused on their ill‐being (e.g., anxiety, depression, and loneliness) and not on their well‐being (e.g., happiness, life satisfaction, and thriving). This entry reviews measures of the components of children's well‐being using quantitative, qualitative, and mixed methods and discusses studies that use these methods to identify the correlates of well‐being in children throughout the world. Children with high positive well‐being tend to have high‐quality social relationships; to display a social, outgoing temperament relatively free of anxiety and shyness; and to report high levels of spirituality. Current research, summarized in this entry, is developing and testing strategies to enhance children's positive well‐being in enduring ways, including strategies that focus on giving and exercises in mindfulness. These strategies need to focus on individual differences and not assume that a single approach will be effective in enhancing the well‐being of all children across all cultures.