After the September 11, 2001 terrorist attacks on the World Trade Center, the New York Philharmonic commissioned Adams to write a memorial piece for the victims of the attacks. The resulting piece, "On the Transmigration of Souls", was premiered around the first anniversary of the attacks. "On the Transmigration of Souls" is scored for orchestra, chorus, and children's choir, accompanied by taped readings of the names of the victims mixed with the sounds of the city. It won the 2003 Pulitzer Prize for Music as well as the 2005 Grammy Award for Best Contemporary Composition.