Historism (Italian: storicismo) is a philosophical and historiographical theory, founded in 19th-century Germany (as Historismus) and especially influential in 19th- and 20th-century Europe. In those times there was not a single natural, humanistic or philosophical science that would not reflect, in one way or another, the historical type of thought (cf. comparative historical linguistics etc.). It pronounces the historicity of humanity and its binding to tradition.

Historist historiography rejects historical teleology and bases its explanations of historical phenomena on sympathy and understanding for the events, acting persons, and historical periods. The historist approach takes to its extreme limits the common observation that human institutions (language, Art, religion, law, State) are subject to perpetual change.

Notable exponents of historism were primarily the German 19th-century historians Leopold von Ranke and Johann Gustav Droysen, 20th-century historian Friedrich Meinecke, and the philosopher Wilhelm Dilthey. Dilthey was influenced by Ranke. The jurists Friedrich Carl von Savigny and Karl Friedrich Eichhorn were strongly influenced by the ideas of historism and founded the German Historical School of Law. The Italian philosopher, anti-fascist and historian Benedetto Croce and his British colleague Robin George Collingwood were important European exponents of historism in the late 19th and early 20th century. Collingwood was influenced by Dilthey.

Ranke's arguments can be viewed as an antidote to the lawlike and quantitative approaches common in sociology and most other social sciences.

The principle of historism has a universal methodological significance in Marxism. The essence of this principle, in brief, is:

not to forget the underlying historical connection, to examine every question from the standpoint of how the given phenomenon arose in history and what principal stages this phenomenon passed through in its development, and, from the standpoint of its development, to examine what the given thing has become today.

— Vladimir Lenin, The State: A Lecture Delivered at the Sverdlov University

20th-century German historians promoting some aspects of historism are Ulrich Muhlack, Thomas Nipperdey and Jörn Rüsen.^{[citation needed]}