This chapter discusses the impact of population ageing and stresses how future improvements in mortality and life expectancy may affect pension systems. The chapter focuses thereafter on how to address the challenges faced by funded pension systems coming from the uncertainty around future improvements in mortality and life expectancy (i.e., longevity risk). It first describes the mortality tables commonly used by pension funds and annuity providers to value their liabilities, then assesses the amount of longevity risk that those mortality tables may implicitly have, and finally discusses policy options to address longevity risk.