Description: This paper presents a stochastic model in continuous time to characterize the ultimate benefit to be derived by a group of similar workers from their career membership in pension plans. This characterization is in terms of termination rates, vesting rules, plan types and periods of employment. The employment termination pattern is represented by a renewal process and a reward function is introduced to unify different plan types. A number of basic functions are then deduced to represent termination benefits, retirement benefits and the loss due to delayed vesting. An analysis of these functions lead to a number of conclusions regarding the comparative effects of delayed vesting in different plans. From Actuarial Research Clearing House 1981, Vol. 1.