In this chapter, we assess the case for mandatory retirement. After briefly considering the issue of age discrimination, we examine a couple of influential arguments in defence of mandatory retirement. Drawing on the work of Edward Lazear, we contend that the most promising basis on which to justify the policy is as a device for employers to structure wage payments over time to optimize workers’ performance. While this argument has some force, we believe that, on closer inspection, it supports a more modest alternative to mandatory retirement whereby employers have the right to reduce the number of hours of older workers. We conclude the chapter by exploring some complexities relating to the fact that economic conditions are not constant across generations.