Friedrich Albert Lange (September 28, 1828 - November 23, 1875), was a German philosopher and sociologist.

Lange was born in Wald, near Solingen, the son of the theologian, Johann Peter Lange. He was educated at Duisburg, Zürich and Bonn, where he distinguished himself in gymnastics as much as academically. In 1852 he became a schoolmaster at Cologne; in 1853 Privatdozent in philosophy at Bonn; and in 1858 schoolmaster at Duisburg, resigning when the government forbade schoolmasters to take part in political activities.

Lange then began a career of militant journalism in the cause of political and social reform. He was prominent in public affairs, yet found enough time to write most of his best-known books, Die Leibesübungen (1863), Die Arbeiterfrage (1865, 5th ed. 1894), Geschichte des Materialismus (1866), and John Stuart Mills Ansichten über die soziale Frage (1866).

In 1866, discouraged by affairs in Germany, he moved to Winterthur, near Zürich, to become connected with the democratic newspaper, Winterthurer Landbote. In 1869 he was Privatdozent at Zürich, and next year professor. The strong French sympathies of the Swiss in the Franco-Prussian War led to his speedy resignation. Afterwards he gave up politics. In 1872 he accepted a professorship at the University of Marburg. Unhappily, his body was already stricken with disease, and, after a lingering illness, he died in Marburg.

His Logische Studien was published by Hermann Cohen in 1877. His main work, the Geschichte des Materialismus is a didactic exposition of principles rather than a history in the proper sense. According to Lange, to think clearly about materialism is to refute it.

There is a comprehensive school named after him, the Friedrich-Albert-Lange-Gesamtschule, in Wald, his birthplace, which is now part of the city of Solingen.