After completing Music for Mallet Instruments, Reich began work on what would become Music for Eighteen Musicians, a piece which would consume his compositional energies for the better part of the next three years. In an interview with the British composer Michael Nyman around the time of Eighteen’s premiere in 1976, Reich speaks about how the piece reflects changes in his musical personality. While Reich’s pieces from around the time of “Music as a Gradual Process” were built on impersonal processes (in contrast to the emphasis on personal expression and free improvisation in the downtown New York music of the time), Eighteen is more concerned with expressive effect. Reich is no longer opposed to using his musical biases to shape the direction of a piece and is less concerned with whether the audience hears the strict processes in it. Music for Eighteen Musicians opens and closes with a series of eleven chords, played in fast quaver pulses by the full ensemble, while the middle sections expand each of the chords into different mini-pieces featuring some of the same rhythmic techniques from Drumming and Music for Mallet Instruments. However, while these processes are simple and certainly audible to a relatively informed listener, they do not draw attention to themselves. The listener is much more drawn in by the hyper-rich instrumental textures and the infectious, nearly tropical, groove.
In order for Eighteen to totally envelop the listener, it must be played with a machine-like consistency. For example, two marimbas play an alternating quaver pulse underneath nearly the entire piece. If one of the players flubs just one beat, the trance-like groove is broken and the piece instantly looses momentum. Despite the performance difficulties, Reich could ensure the piece’s performance quality because he had over the past several years assembled a dedicated group of musicians to play his music with him. While composing Drumming in 1970, soon after a trip to study drumming in Ghana, Reich was introduced to a percussionist named Russell Hartenberger who was also interested in travelling to Africa. Through his conversations with Reich, Hartenberger was invited to rehearse the incubating Drumming and became the first full-time percussionist in Reich’s ensemble. To meet the eventual playing demands of Drumming (it requires 9 percussionists), Reich brought in other percussionists, many through James Preiss, a teacher at the Manhattan School of Music. As Reich’s reputation grew within the underground New York contemporary music scene, he was able to draft even more players into Steve Reich & Musicians, eventually reaching the core of 17 (plus himself) in the mid 1970s. Reich notes in a 2002 interview that most the musicians he was working with at the time of Eighteen were still finishing up graduate school, so it was not difficult to bring everyone in for a rehearsal every 2-3 weeks.
Reich’s working band not only allowed the composer to more tightly control the performance quality of his pieces, it also had a profound effect on Reich’s compositional process as well. In Drumming, for instance, the human phasing techniques had never been employed in any piece of music before and so it required that Reich learn how to do it himself (phasing against a tape loop) and then teach the technique to his players. Notation alone would not have been able to adequately express the sound of the piece. This rote method of learning Drumming carried over to Eighteen as well. Throughout 1974-1976, Reich would work on a particular segment of the piece in his manuscript notebook (see the “pulses” example below), and then would transcribe it out in a shorthand notation on small slips of paper for each player. Most of the details of the piece were worked out during the rehearsals themselves. Russell Hartenberger notes that each part was like a cliffnotes version of the piece, with very personalized directions (i.e. “wait for Jay to sing that pattern, cue Steve.”). At each rehearsal, Reich would bring in corrections and take suggestions from the players. In this way, the composition of the piece and the learning of the piece were one process, much more akin to the members of a rock band composing and learning a song together. In both instances, the piece or song is composed into the muscle memory of the players, making a written score unnecessary.
 Michael Nyman, “Steve Reich: Interview by Michael Nyman,” Studio International, 1976, no. 192 (November / December): pp. 300-307.
 Interview with Russell Hartenberger by Daniel Tones.
 Gabrielle Zuckerman, Interview with Steve Reich, July 2002, http://musicmavericks.publicradio.org/ features/interview_reich.html.
 Hartenberger Interview.
 Steve Reich, Music for Eighteen Musicians, performance note, London: Boosey & Hawkes, 2000.
 Hartenberger Interview.