T IME affects an individual's earnings in three ways. First, his earnings depend on his age and experience, as he acquires skills through experience or as his productivity changes during the aging process. Second, the rental rate on human capital varies over time with relative factor supplies, consumer demand, and technical change. Finally, workers in different cohorts may attain different earnings levels for a variety of reasons. Common experiences of certain cohorts, such as war or depression, may permanently affect their lifetime careers, as might the quality of schooling received by the cohort, or the tightness of the labor market as the cohort entered its first jobs. This paper attempts to estimate these on the earnings of white American men by using panel data on a cross-section of workers. The estimated vintage effects, beside being of interest for their own sake, allow at least tentative evidence on several recent hypotheses about the labor market. Vintage effects for this paper are defined as the differences in earnings between cohorts that cannot be explained by either secular growth or the normal age-experience profile of earnings. A cohort is defined as a set of all workers who entered the labor force at the same time. Since cohort effects, as defined, must have lasted into the observation period, 1968-76, to be observed, we cannot measure any temporary advantage or disadvantage a cohort may have held before the observation period. The estimates, therefore, attempt to measure long-run effects of vintage on earnings or the long-run difference between cohorts abstracting from age and calendar time. The major problem in the analysis is to disentangle empirically the effects of age, time, and vintage on earnings. At the very least, one must observe cross-sections of workers at different points in time. However, a further necessary condition is some restriction on the functional form which allows vintage effects to be identified. This problem is handled in two ways: 1. restrictions on the functional form of the earnings function that are robust to alternative functional forms; 2. direct tests of alternative hypotheses about the cause of vintage effects.