Equivalence was a key word in the linguistics-based translation theories of the 1960s and 1970s, although its basic mode of thought may be traced back to Cicero and later to the Renaissance theories that began to presuppose languages of equal status. Close inspection reveals that some theories assume pre-existing equivalents and are thus concerned with a search for “natural” equivalence. Other theories allow that translators actively create equivalents, and are thus concerned with “directional” equivalence. The first kind of equivalence is concerned with what languages ideally do prior to translation; the other deals with what they can do. These two approaches are often intertwined, giving rise to many misunderstandings and unfair criticisms of the underlying concept. The historical undoing of the equivalence paradigm came when the directional use of the term allowed that equivalence need be no more a belief or expectation at the moment of reception, which need not be substantiated on the level of linguistic forms. At the same time, source texts became less stable and languages have been returning to more visibly hierarchical relations, further undermining the concept. Contemporary localization projects may nevertheless fruitfully be interrogated from the perspective of natural and directional equivalence, since the presumptions are being used by contemporary technology precisely at the moment when the terms themselves have been dropped from critical and exploratory metalanguage.