Stevens succeeds American Lawton Fitt, one of several top executives whose resignation was announced by the Royal Academy in the past year as the result of executive in-fighting and disagreements.
A spokesman for the academy said it hopes by summer to appoint a permanent secretary, who would be the chief administrator, after a review of governance of the institution. Stevens has worked closely with Norman Rosenthal, the academy's exhibitions secretary.
Although a British institution, the Royal Academy has had a history of American associations. One of its founders in 1768 was Pennsylvania-born Benjamin West who became its president in 1792, succeeding Sir Joshua Reynolds.