Description: This paper is part of The research project dealing with pension accounting, more precisely with Statement of Financial Accounting Standards No. 87 [or FAS 87]. The goal of the project is to study the variability of pension accounting costs under FAS 87. In this paper, the author addresses only one specific point, namely the behavior of experience gains and losses over time. This is directly related to the corridor approach to amortization of gains and losses. However, what is said also applies to experience gains and losses in other areas, particularly in pension funding and insurance. From Actuarial Research Clearing House 1993, Vol. 1.