This paper aims at formulating a theoretical model of educational attainment which is directly implementable empirically. The conceptual frame-work relies on the human capital theory, where individuals weigh the costs and the returns of education to decide on the optimal amount of education they want to invest in. In an extension of the model, the educational process is de- composed into two stages: achievement at school and post-school achievement. The same conceptual framework applies at both stages, but a correlation is permitted between them. Empirically, this boils down to estimate a multivariate ordered probit model. An illustration based on German data shows how this model functions in practice. Thus, the model confers an economic foundation on the empirical estimation of the impact of certain factors on educational outcomes.