A particularly important issue in retirement income provision is longevity risk. There are two components to longevity risk. The first is the uncertainty over how long any particular pension scheme member is going to live after retirement. This is known as idiosyncratic longevity risk. Both individuals and schemes face idiosyncratic longevity risk. The second is uncertainty over how long members of a particular age cohort are going to live after retirement. This is known as systematic longevity risk. Only schemes face systematic longevity risk. Individuals have a poor understanding of idiosyncratic longevity risk. Pension schemes can reduce idiosyncratic longevity risk by pooling the risk amongst a large number of scheme members, i.e., by taking advantage of the law of large numbers. Systematic longevity risk, however, cannot be reduced in this way: it needs to be hedged using a suitable hedging instrument.