Robert Lansing (/ˈlænsɪŋ/; October 17, 1864 – October 30, 1928) was an American lawyer and diplomat who served as the 42nd United States Secretary of State under President Woodrow Wilson from 1915 to 1920. As Counselor to the State Department and then as Secretary of State, he was a leading advocate for American involvement in World War I.
Lansing was born and raised in Watertown, New York, where he joined his father's law firm after graduating from Amherst College. After developing expertise in international law and marrying the daughter of Secretary of State John W. Foster, he served as associate counsel to the United States delegations to the Bering Sea Arbitration and Bering Sea Claims, before arguing the United States case before the Alaska Boundary Tribunal in 1903.