Gilbert attended school in St. Paul, Minnesota, before taking his degree at the Massachusetts Institute of Technology, Cambridge. In 1880, following a tour of Europe and Egypt, he began his professional career by becoming the personal assistant of Stanford White. Three years later he went to St. Paul and with James Knox Taylor established his own office.
In the 1890s Gilbert began moving toward a more formal style of neoclassicism than that associated with McKim, Mead and White. Beginning with the Minnesota State Capitol Building, 1895, his commissions became increasingly more important. By 1899 he had moved his headquarters to New York, where in 1912 he erected perhaps his most celebrated accomplishment, the Woolworth Building.
As his fame grew, Gilbert assumed important positions in national artistic and architectural circles. At various times, he served as president of the American Institute of Architects, the Architectural League, and the National Institute of Arts and Letters. At the National Academy, he was a member of the Council from 1909 to 1912, and was president from 1926 to 1933, the first architect to hold an Academy officership.
Cox was a natural choice to execute Gilbert's Associate portrait, for they had collaborated on several occasions, with Cox murals embellishing Gilbert's Minnesota State Capitol Building, Essex County (New Jersey) Courthouse, and Citizens Bank, Cleveland, Ohio. In writing in 1910 to a colleague he was trying to persuade not to decline election to the Academy because of the difficulty of fulfilling the portrait requirement, Gilbert said Cox had painted his portrait "on two Sundays." Some exaggeration in this statement must be allowed in the circumstances; it is more likely that the portrait was based on two sittings. Cox thought it one of his best portraits, as he wrote to his friend, Leonard Opdycke, in 1914.
