Carnegie Hall, the older and richer of the two organizations, will apparently be the senior partner: Sanford I. Weill, its board chairman, will also chair the new partnership board, and Clive Gillinson, its executive and artistic director, will be president of the partnership organization. Their opposite numbers at City Center, board chair Raymond A. Lamontagne and CEO Arlene Shuler, will be vice chairman and vice president of the new structure.

A statement from the two organizations said that each venue will maintain its own identity: Carnegie Hall as a leading presenter of music, and City Center, the home of Alvin Ailey American Dance Theater, American Ballet Theatre, and the Encores musical-theater series, as a venue for dance and musicals. But they will also "leverage power artistic synergies across the organizations. "

"Imagine a thematic festival that can draw simultaneously on newly commissioned music, dance, and theater works," said Gillinson, "with performances by symphony orchestras, dance companies, poets, theater companies, chamber ensembles, and recitalists, all in a coherently conceived festival with robust, complementary educational programs."

The first joint effort by the two organizations will be a $150 million renovation of City Center, to begin in 2007. It will include an overhaul of the main auditorium and the creation of new educational space that will be used by both organizations.

The announcement today of a "memorandum of understanding" between the two venues comes two and a half years after Carnegie Hall and the New York Philharmonic announced that they would merge. That more ambitious agreement—it included the combination of the organizations' boards and staff—eventually fell apart as it became clear that the differing priorities of the two groups (and their powerful leaders) could not easily be reconciled.