In this chapter, we start with a description of happiness, the nature of happiness, the value of happiness, and the determinants of happiness. In that context, we discuss what leisure can contribute to happiness. Although happiness is partially set through inherited personality traits, there is potential for improving one's sense of happiness through leisure. Research to date focused mainly on casual leisure and leisure travel. These kinds of leisure have mostly a small positive effect on happiness. The benefits are often temporary and in the moment. We propose more longitudinal research that addresses serious leisure and project-based leisure, which may have more sustained effects on happiness than casual leisure and leisure travel.