This chapter reviews the literature about the effect of retirement on well-being. It distinguishes studies that investigate the consequences of retirement on measures of well-being such as happiness and life satisfaction from those focusing on mental health. Special attention is also paid to the estimation method and the identification strategy. While results based on mental health or measures of well-being are remarkably consistent, they are sensitive to the estimation methods. While, on average, retired individuals report a lower level of well-being than workers, results based on causal methods tend to indicate that the effect of retirement on well-being is nonnegative.