 Many scientists, philosophers, and laypersons have regarded science as the one human enterprise that successfully escapes the contingencies of history to establish eternal truths about the universe, via a special, rational method of inquiry. Historicists oppose this view. In the 1960s several historically informed philosophers of science challenged the then-dominant accounts of scientific method advanced by the Popperians and the positivists (the logical positivists and logical empiricists) for failing to fit historical scientific practice and failing particularly to account for deep scientific change. While several strands of historicism originated in nineteenth-century historiography, this article focuses, first, on the historicist conceptions of scientific rationality that became prominent in the 1960s and 1970s, as the maturation of the field of historiography of science began to suggest competing models of scientific development, and, second, on recent approaches such as historical epistemology.