The paper develops a model of retirement based on the option value of
continuing to work. Continuing to work maintains the option of retiring on
more advantageous terms later. The model is used to estimate the effects on
retirement of firm pension plan provisions. Typical defined benefit pension
plans in the United States provide very substantial incentives to remain with
the firm until some age, often the early retirement age, and then a strong
incentive to leave the firm thereafter. (This may be a major reason for the
rapidly declining labor force participation rates of older workers in the
United States.) The model fits firm retirement data very well; it captures
very closely the sharp discontinuous jumps in retirement rates at specific
ages. The model is used to simulate the effect on retirement of potential
changes in pension plan provisions. Increasing the age of early retirement
from 55 to 60, for example, would reduce firm departure rates between ages 50
and 59 by almost forty percent.