The chairman of the board of trustees of the Hirshhorn Museum and Sculpture Garden, J. Tomilson Hill, has resigned, the Hirshhorn announced this week.

Hill, 63, president and chief executive of Blackstone Alternative Asset Management and a vice chairman of the Blackstone Group, joined the board in May 1999 and became chairman in 2004.

“After eight years as chairman, I decided that it was the right time to step down,” Hill said in a statement. “It is my great hope that the Hirshhorn will continue its commitment to organizing world-class exhibitions, supporting emerging artists and adding great works to the collection. With a talented and diverse group of curators, I know the Hirshhorn will thrive well into the future.”

Hill “has devoted countless hours to the museum, advising the director and its senior staff members, as well as other leaders at the Smithsonian. Bringing to the task a deep appreciation for contemporary art, he has helped shape the Hirshhorn into a museum that serves as a platform for inspiration and understanding,” the Hirshhorn said in the announcement.