John Lambert Cadwalader (November 11, 1836 – March 11, 1914) was an American lawyer.

Cadwalader was born in Trenton, New Jersey, on November 17, 1836. He was the eldest son of General Thomas McCall Cadwalader (1795–1873) and the former Maria Charlotte Gouverneur (1801–1867). His siblings included Emily Cadwalader (wife of William Henry Rawle), Mary Cadwalader (wife of Dr. Silas Weir Mitchell), Richard McCall Cadwalader (husband of Christine Biddle), and Maria Cadwalader (wife of John Hone).^[1]

On his paternal side, his grandfather was Lambert Cadwalader, and his great-grandfather was Thomas Cadwalader.^[1] His maternal uncle was Samuel L. Gouverneur. His mother was a niece of Elizabeth (née Kortright) Monroe, the wife of U.S. President James Monroe.^[1]

He graduated from Princeton University in 1856, then obtained an M.A. degree in 1859 from Princeton, and LLB from Harvard Law School in 1860.^[2]

He served as United States Assistant Secretary of State from 1874 to 1877, serving under Republican Presidents Ulysses S. Grant and Rutherford B. Hayes and Secretaries Hamilton Fish and William M. Evarts. In 1878, he became a name partner of Cadwalader, Wickersham & Taft, the oldest continuously operating law firm in the United States, which still carries his name.^[3] In 1905 he became a life member of the American Academy in Rome, where he acted as an adviser during the Academy's incorporation process.^[4] From 1906 to 1907, he served as president of the New York City Bar Association.^[5] He was an early trustee of the Carnegie Endowment for International Peace.^[6]

In 1909, he was mentioned as the successor of Whitelaw Reid as the U.S. Ambassador to the United Kingdom under President William Howard Taft, as urged by Taft's Attorney General George W. Wickersham, but Taft "finally decided to retain Mr. Reid."^[2]

Cadwalader was at one time president of the New York City Bar Association, but his most prominent connection in the minds of the public was with the New York Public Library, of which he was elected the second president, as the successor of John Bigelow. For many years before his election to this office, he had been a member of the board of trustees and of the executive committee of the library. He probably did more, in the form of personal activities, for the library service of New York City than any other man. He worked out the plans for combining the Astor, Lenox, and Tilden foundations into one great, central library, and was instrumental in the material carrying out of this conception. He also devoted a great deal of thought to the planning out of the building that housed the library.^[7]

Cadwalader was a trustee of the Metropolitan Museum of Art, and left the furnishings of his home on East 56th Street to the museum.^[8] He was a trustee of the Carnegie Institution from 1903 until he died in 1914.^[9] In 1912,^[10] he was sketched by John Singer Sargent.^[11]

He was on the board of the New York Zoological Society (now Wildlife Conservation Society). He was a member of the Society of the Cincinnati, the Sons of the Revolution, the American Fine Arts Society, and the American Museum of Natural History. His clubs included the Century Association, the Union League Club, Lawyers' Club, Union Club, Metropolitan Club, Knickerbocker Club, University Club, Princeton Club, and New York Yacht Club, all of New York City.^[7]

Cadwalader never married.^{[7][lower-alpha 1]}

On March 11, 1914, Cadwalader died at his home at 3 East 56th Street in Manhattan, at age 77.^[2] After a funeral at Grace Church in Manhattan, he was buried at Woodlands Cemetery in Philadelphia.

In his will, he left to "each of the clerks in the office of Strong & Cadwalader," who had been working for the firm for five years prior to his death, "a sum of money equal to six times their monthly wage."^[12]