The Atlanta Symphony Orchestra Choruses—the Atlanta Symphony Orchestra Chorus (ASOC) and the Atlanta Symphony Orchestra Chamber Chorus (ASOCC)—have become exemplars for the performance of choral-orchestral repertoire. Exhibiting the highest professional technique yet infused with the unqualified love and commitment of their volunteer members, the ASO Choruses are an enduring legacy of their founder, Robert Shaw. The purpose of this dissertation is to examine and formally document how the Atlanta Symphony Orchestra Choruses were formed, how they grew and flourished, and how they have continued to thrive under new artistic leadership. Robert Shaw founded the Atlanta Symphony Orchestra Chamber Chorus (ASOCC) in 1967 followed by the Atlanta Symphony Orchestra Chorus (ASOC) in 1970 to perform choral-orchestral masterworks with the Atlanta Symphony Orchestra as a core component of its repertory. Shaw and his assistants employed specific organizational and musical systems to form and build the ASO Choruses. Shaw transformed these choruses into world-class ensembles through uncompromising discipline and a firm belief in the power of unison singing. The resulting unanimity—a hallmark of the ASO Choruses—was heard in every aspect of the sound of the ASO Choruses. This sound was characterized by warmth and roundness, exceedingly crisp diction, immaculate dynamic control, precision of pitch and metrics, and the smoothness and transparency of a chamber ensemble. Shaw worked tirelessly to develop a community of musicians and supporters that cared deeply about music and the Arts. The ASO Choruses, while auditioned, were volunteer ensembles in contrast with other notable symphony choruses, such as those of Chicago and San Francisco, which had a paid contingent of singers. The ASO Choruses were unique for having attained an extremely high level of excellence while remaining entirely volunteer. Chorus members committed substantial time and effort in support of their common love of music and excellence. The ASOC made its Carnegie Hall debut in 1976, and the ASO Choruses have returned there over twenty times. The ASOC made history on its international debut tour as part of the largest American performing arts organization to travel to Europe. More recently, the ASOC traveled to Berlin in three different seasons to perform with the Berlin Philharmonic. The ASOC has a significant, award-winning discography of over fifty recordings, including nine Grammy Awards for Best Choral Performance. Today, the ASO Choruses continue to uphold the legacy established by their founder, Robert Shaw. Under the present leadership of Norman Mackenzie (Director of Choruses), Robert Spano (Music Director), and Donald Runnicles (Principal Guest Conductor), the Choruses have engaged in new ventures that combine various art forms in an expanding repertory, which includes numerous commissions and premieres. In so doing, the ASO Choruses honor the vision for which the Atlanta Memorial Arts Center was created.