Holst was a Baltic German born at Fellin (Viljandi) in Russian Livonia. He was educated at the universities of Dorpat (Tartu) and Heidelberg, receiving his doctor's degree from the latter in 1865. He immigrated to the United States in 1867, remaining there until 1872.
He was professor of history in the newly reorganized University of Strasbourg from 1872 to 1874, and at University of Freiburg in Baden from 1874 to 1892, and for ten years he was a member of the Baden Herrenhaus, and vice-president for four. He revisited the United States in 1878-79 and in 1884, and in 1892 he became head of the department of history at the University of Chicago. Retiring on account of ill-health in 1900, he returned to Germany and died at Freiburg in January 1904.
Both through his books and through his lectures at the University of Chicago, Holst exerted a powerful influence in encouraging American students to follow more closely the German methods of historical research. His principal work is his Constitutional and Political History of the United States (German ed., 5 vols., 1873-91; English trans. by Lalor and Mason, 8 vols., 1877-92), which covers the period from 1783 to 1861, though more than half of it is devoted to the decade 1850-60; it is written from a strongly anti-slavery point of view. Among his other writings are The Constitutional Law of the United States of America (German ed., 1885; English trans., 1887); John C. Calhoun (1882), in the American Statesmen Series; John Brown (1888), and The French Revolution Tested by Mirabeau's Career (1894).
See the Political Science Quarterly, v. 677-78; the Nation, Ixxviii. 65-67.