This paper acknowledges that the relationship between log wages and schooling is considerably more complex than the simple human capital earnings function suggests and that schooling is endogenous. We estimate a model where educational attainment is discrete and ordered and log wages are determined by a simple function of work experience for each level of attainment. We distinguish between lifecycle and cohort effects by exploiting the fact that we have a short panel. We strongly reject both the usual separability assumption and exogeneity
of educational attainment.