Griscom grew up among the social elite of Philadelphia; but the luxury of wealth was tempered by the family's Quaker heritage and, for him, by the austere regimens of the private schools he attended in Switzerland, Paris, and Philadelphia. After receiving the B. Phil. in 1891 from the University of Pennsylvania, Griscom entered the university law school but left in 1893 because of poor health. After returning home in September 1894, he resumed his law studies at the New York Law School and completed them two years later.
Soon after leaving the law school, Griscom secured appointment as unpaid private secretary to Thomas F. Bayard, newly appointed United States ambassador to Great Britain. During the next year Griscom had his first experience of the diplomatic world and began a lifelong acquaintance with the British aristocracy. From January to April 1895, he accompanied the noted writer Richard Harding Davis on a journey later described in Davis' Three Gringos in Venezuela and Central America (1896). He then completed his studies and was admitted to the New York bar in 1896. After a brief term in 1897 as deputy assistant district attorney of New York City, his health again declined and Griscom moved to Arizona to recover. He left there to enlist for service in the Spanish-American War, and was commissioned a captain in the Army Quartermaster Corps in May 1898. Made aide-de-camp to Major General James F. Wade, Griscom spent the war months in an army camp in Georgia. In September 1898 he accompanied General Wade to Cuba, where Wade headed the United States commission that arranged the evacuation of the Spanish forces from the island. He returned home and was discharged in January 1899. Determined to return to diplomatic service, Griscom used his father's influence to secure appointment as secretary of the United States legation at Constantinople. He became chargé d'affaires in December 1899, when Minister Oscar Straus returned home on leave. Straus did not resume his post; and for the next fifteen months Griscom, not yet thirty years old, conducted a vigorous campaign to persuade the Turkish government to pay $90, 000 to United States citizens as settlement of claims arising from the Armenian massacres of 1894. Using the visit of an American battleship to imply the threat of force, he finally collected the money. This established his reputation with Secretary of State John Hay, and he was made minister to Persia. Late in 1902 Griscom achieved senior diplomatic status with his appointment as minister to Japan, where he served during the Russo-Japanese War of 1904-1905. Although the post was a responsible one, most of the diplomatic activity that led to the peace conference at Portsmouth, New Hampshire, occurred in Washington and St. Petersburg, the Japanese having desired the conference from the start. Furthermore, Griscom found himself handicapped by his extreme youth in a land where age and status were closely associated. Nevertheless, he was regarded by President Theodore Roosevelt as having performed creditably; and in 1906 he became United States ambassador to Brazil. His main duty there was to prepare for the visit of Secretary of State Elihu Root to the Pan-American Conference at Rio de Janeiro. At the end of the year Griscom was named to his last and highest post, that of United States ambassador to Italy. He served in Rome from 1907 to 1909, and took a leading part in organizing relief work after the great Messina earthquake of December 27, 1908. The advent of the William Howard Taft administration in 1909 ended Griscom's diplomatic career. The policy of promotion for merit and retention of able men in the diplomatic service, put into practice by John Hay and Theodore Roosevelt, was counter to the political patronage tradition; and Taft's term saw a revival of the older practices. Griscom had thus been one of a small body of American diplomats who for a time had enjoyed something like career status, his youthfulness and meteoric rise making him perhaps the most striking example of them all. Returning to New York to practice law, Griscom was briefly involved in politics. Upon United States entry into World War I in 1917, he joined the army as a major in the Adjutant General's Corps and served in France with the Seventy-seventh Division (1918). In France, General John J. Pershing, who had been military attaché at Tokyo when Griscom was there, detached Griscom to serve in London as his personal liaison with the British War Office. In this obscure but important post, Griscom brought his diplomatic skills to bear on behind-the-scenes frictions among the Allies. He was promoted to lieutenant colonel; and after the armistice he received the Distinguished Service Medal, and King George V made him a knight commander of St. Michael and St. George. After the war Griscom was president of the Huntover Press, which published daily and weekly newspapers on Long Island. In later life he was coauthor of a drama, Tenth Avenue, which was made into a motion picture, and wrote a volume of memoirs entitled Diplomatically Speaking. He died at Thomasville, Georgia, on February 8, 1959.
President of the New York County Republican Committee (1910-1911)
Griscom was intelligent, energetic, and a good organizer. An amateur linguist, he learned nine languages and wrote English prose with wit and facility. Although he mixed well with all sorts of people, he was always an aristocrat in manner and outlook, and his career owed much to his privileged beginnings.
Griscom married Elizabeth Duer Bronson, whom he had met in Constantinople, on November 2, 1901. They had two sons. She died in 1914 and in 1929 Grisocom married Audrey Margaret Crosse; they had no children.