Diplomatic career
In June 1891, after Anderson had dropped out of Harvard Law School, his father interceded with his 1858 Harvard classmate Robert Todd Lincoln, son of President Abraham Lincoln, who was then serving as the U.S. minister to the Court of St. James's in London. Lincoln offered Anderson the job of second secretary of the American legation in London. In 1894, after three years in London, Anderson was appointed first secretary of the American embassy in Rome and then, in 1897, served for several months as chargé d'affaires, until he resigned to return to the U.S. for his wedding to Isabel Weld Perkins. His resignation was at the time controversial, and American newspapers reported on his months-long efforts to be released from his post by the U.S. Department of State.
Anderson returned to the diplomatic corps in 1911 as United States Minister to Belgium, serving from November 18, 1911 until November 15, 1912, when he was appointed Ambassador to Japan. He held this post as a fully accredited and confirmed American ambassador for only one day, March 3, 1913, though he was in Japan from December 28, 1912, until his return to the United States on March 16, 1913. He resigned when the Republican administration of William Howard Taft was replaced by the Democratic administration of Woodrow Wilson. The exact reasons for his resignation and departure from Japan are not clear. One American newspaper reported that he left his Tokyo post "because the Japanese government had declined to receive him."
When Anderson was appointed Minister to Belgium, he had an elaborate diplomatic uniform made for himself in London by the firm of Davies & Son, tailors to British royalty. Though he was famously photographed and painted wearing it, he never wore the elaborate, custom-made quasi-military uniform in public, once writing in his journal that the "Diplomatic uniform is in the dress of a minister of the 'first-class' (which I am) and is the one which I do not wear." Some have claimed based on the photograph that Anderson's uniform was one of the few worn by an American diplomat since the early 1800s, but a public law dating to 1867 prohibited diplomats from wearing any uniform not approved by Congress, and Anderson observed that law. In 1937, President Franklin Roosevelt proscribed American diplomats from wearing any uniform. Anderson's uniform is on display at Larz Anderson House.
Though it has often been said that he "retired from the diplomatic corps" after leaving Japan, he remained open to another assignment. In 1923 he actively though unsuccessfully sought nomination as U.S. Ambassador to Rome under President Calvin Coolidge. He later recalled that he was "the first American to rise all the way through the diplomatic ranks from the lowest position to the highest." Anderson and his wife, Isabel, spent the next twenty-five years traveling extensively at home and abroad; collecting memorabilia and decorative arts; expanding the mansion and gardens of their summer home "Weld" in Brookline, Massachusetts, now the Larz Anderson Park; funding the construction of the Anderson Memorial Bridge across the Charles River in Boston and Cambridge, Massachusetts; and funding the construction and interior decoration of the Lady Chapel of the Washington National Cathedral.
According to sources cited by his biographer, Anderson's diplomatic record was an embarrassment to President William Howard Taft; the Senate Foreign Relations Committee refused to confirm him as United States Ambassador to Japan in 1913 even after he had assumed his post there. Richard W. Leopold, reviewing a volume of Anderson's letters, wrote that they contained "little of value":
Comments on those vital economic, social, and intellectual forces that shape foreign policy are wholly absent. Anderson seems to have been blissfully unaware of or unconcerned with the factors making for Anglo-American friendship in the early [eighteen]-nineties. His diaries shed no new light on Italian-American relations during the same decade. Although he was at Brussels just before the World War and at Tokyo in a critical moment in Far Eastern affairs, Anderson recorded nothing of importance. Instead, his pages are devoted solely to royal receptions, embassy parties, and other trivialities that are merely the trappings of diplomatic life.
George E. Mowry wrote that Anderson "never allowed his official duties to interfere with his lengthy and verbose unofficial reporting of society's meaningless activities ... If the selections published are a true sample of the bulk of the writings that Mr. Anderson chose to preserve for posterity, they say little for the author and as little for the government that hired him for responsible positions."