This chapter summarizes and evaluates existing research on prenatal mental health and emotional distress during pregnancy. First, the prevalence and correlates of prenatal mental health problems, including psychiatric conditions (e.g., major depression and anxiety disorders) and non-clinical affective states, are described. Second, mental and physical health effects of elevated stress during pregnancy are discussed. Associations of prenatal mental health problems and stress with adverse birth outcomes, long-term maternal mental health, and child developmental problems are reviewed. Third, selected risk and resilience factors are discussed, including racial/ethnic discrimination, social support, and coping. The complex and context-dependent nature of these risk and resilience factors is highlighted. Finally, a brief summary of the current status of interventions for prenatal maternal distress is provided. Research on prenatal distress interventions is in its nascency, but available evidence highlights the promise of multimodal mind-body interventions.