Emily Rafferty, who has been the president of the Metropolitan Museum of Art for more than a decade, announced Thursday that she will be retiring in the spring of 2015.

"With the ebb and flow of projects, this feels like the right time. Nobody takes a decision like this without serious thought," Ms. Rafferty, 65, said.

Her retirement comes as the museum prepares to embark on a series of new initiatives and a related long-term capital campaign. She also cited a number of projects she shepherded that are well underway or nearing completion, such as the Costume Institute, which opened in May, and the plaza renovation project, which is scheduled to be completed in the fall of 2014.