In advanced capitalist countries, the shaping of a relatively homogeneous wage-earning class was a slow process that lasted, at least three generations. This gradual transition to a wage-earning economy does not seem to have taken place in developing countries, where the existence of a wide informal sector encompasses a series of consecutive phases in advanced capitalist countries in a complex way. More than a form of transition, the informal sector appears as a particular type of economic organisation. This sector, internally, and when joined with the formal economy, develops a special rationality that cannot be explained by interpretations underlying the policies directed towards this sector; such a rationality suggests a new type of policy -that of taking the sector's pecularities into account-and goes beyond the plain assistence treatment and simplifying attempts of formalising the informal.