Mental health problems are highly prevalent, associated with a large burden of disease and associated with lower socioeconomic outcomes. However, up until recently, mental health has been largely ignored by economists. This is problematic because mental health might differ from physical health on some key aspects: mental health problems often start early in life, in contrast to most physical health problems, and mental health problems might affect decision-making in ways distinct from physical health problems. Consequently, this thesis investigates mental health and its consequences at different points in the lifecycle