 The correspondence principle was first articulated in 1913 in the context of the old quantum theory. Nonetheless, Bohr argued that this principle survived the replacement of the old quantum theory by modern quantum mechanics. The correspondence principle is still referred to today in the physics literature as a subject of current research, though arguably with a meaning that is somewhat different from Bohr’s own understanding of this principle. A version of the correspondence principle also lives on in the philosophical literature where it has been generalized into a broad methodological principle (the generalized correspondence principle) constraining the development of new scientific theories.