With the 2006 opening of its expansion designed by the Renzo Piano Building Workshop, The Morgan Library and Museum in New York began a new chapter in its history.This is an illustrated chronicle of the one-hundred-year transformation of a rarefied private library into an acclaimed public museum. The contributors assess Pierpont Morgan's vision for his personal library, provide historical context for its public evolution and examine the process of the expansion; and in an interview, Piano discusses his role.