The gift, which has doubled the company's endowment, is among the largest single gifts to a theatre company in U.S. history, according to the Huntington.

Founded by the late Stan and Norma Jean Calderwood, the foundation previously presented the Huntington with a $4 million grant in 2004 for the Calderwood Pavilion located at the Boston Center for the Arts. Previous gifts also include personal endowments totaling $3 million from Mr. Calderwood and $1.5 million dispersed over the past three years.

"The Huntington has earned its standing as one of Boston's legacy cultural institutions, and its board of trustees is committed to assuring its continued health and artistic vitality for future generations," board chairman Carol Deane said in a statement. "This gift makes the Huntington stronger and more secure than ever before, but it does not alone guarantee our success. Therefore, we will use this generous gift as a catalyst and a challenge, launching a careful examination over the next twelve months of the Huntington’s long-term needs. The end result will be a plan that ensures the Huntington's status as a major contributor to the cultural life of Boston for many years to come."

The Huntington recently staged the world premiere of Stephen Karam's Sons of the Prophet, which will arrive Off-Broadway this fall at the Roundabout Theatre Company.

The 2011-2012 season will include Mary Zimmerman's Candide and the Tony-winning comedy God of Carnage. Visit Huntington Theatre.