In 2011, the National Prevention, Health Promotion, and Public Health Council named mental and emotional well-being as 1 of 7 priority areas for the National Prevention Strategy. In this article, we discuss emotional well-being as a scientific concept and its relevance to public health. We review evidence that supports the association between emotional well-being and health. We propose a national emotional well-being initiative and describe its 6 components: systematic measurement of emotional well-being, identification of the drivers of emotional well-being, formation of partnerships with diverse stakeholders, implementation and dissemination of evidence-based interventions to promote emotional well-being and its drivers, development of public health messaging, and identification of and strategies to address disparities in emotional well-being and its drivers. Finally, we discuss ways in which a national emotional well-being initiative would complement current public health efforts and the potential challenges to such an initiative.