This paper builds a multi-sector labor market model including wage dualism, open unemployment, underemployment, on-the-job search, and expected wage equalization. The innovative feature of this model is the distinction between the ex ante allocation of the labor force among search strategies and the ex post allocation of the labor force among labor market outcomes. Among the findings are: more efficient on-the-job search lowers the equilibrium unemployment rate; in a rational expectations equilibrium, the average rural and urban wages will not be equal; modern sector enlargement may leave labor market conditions in one of the sectors unchanged, even when wages and employment in that sector are fully flexible.