By Patrick Healy for The New York Times — The family foundation of Barry Diller and Diane von Furstenberg has made its largest donation to an arts organization, $3 million to Signature Theater Company for its new Off Broadway home set to open in February. James Houghton, artistic director of the theater company, announced the gift for the Signature Center complex on Thursday and said that in appreciation the centerpiece stairway would be named the Diller-von Furstenberg Grand Staircase.

Mr. Houghton said that Mr. Diller, the chairman of IAC and Expedia, and Ms. Von Furstenberg, the designer, were introduced to Signature by the actor Edward Norton, who is a board member of the theater company and a co-chairman of its capital campaign.The couple’s foundation has donated to New York education, arts, and civic organizations since its creation in 1999, including a $20 million gift this fall for further expansion of the High Line park on the West Side of Manhattan.

The $66 million Signature Center project, designed by Frank Gehry, includes city financial support and several major gifts from board members and others, including a $5 million donation in honor of the playwright Romulus Linney, whose name was bestowed on one of its three new theaters. Signature, which Mr. Houghton founded in 1991, is moving into the center on West 42nd Street this winter from its single-theater home farther west on the same street.