 Equality of opportunity is a political ideal that is opposed to caste hierarchy but not to hierarchy per se. The background assumption is that a society contains a hierarchy of more and less desirable, superior and inferior positions. Or there may be several such hierarchies. In a caste society, the assignment of individuals to places in the social hierarchy is fixed by birth. The child acquires the social status of his or her parents at least if their union is socially sanctioned. Social mobility may be possible in a caste society, but the process whereby one is admitted to a different level of the hierarchy is open only to some individuals depending on their initial ascriptive social status. In contrast, when equality of opportunity prevails, the assignment of individuals to places in the social hierarchy is determined by some form of competitive process, and all members of society are eligible to compete on equal terms. Different conceptions of equality of opportunity construe this idea of competing on equal terms variously.