The purpose of this study was to chronicle the genesis of cultivated choral tone in the United States from 1906 to 1928. That transformation was led by three conductors whose disparate careers represented a shared trajectory. Individually and collectively, they pioneered two singing genres with European provenance--a cappella and senza vibrato singing--as early techniques to isolate and refine choral tone. Their work converged in 1928, when it expanded to become the American A Cappella Movement (1928-1938). The earliest of the three conductors was Peter C. Lutkin (1858-1931). After study in Europe, he became dean of the School of Music at Northwestern University. Through his publications and university a cappella choir, founded in 1906, he placed greater responsibility on singers, and employed diction and breath control to improve intonation and tonal purity. German-educated Norwegian-American F. Melius Christiansen (1871-1955) was guided by his experience as a violinist and influenced by the choir of St. Thomas Church, Leipzig, Germany. In 1907, he began to gradually transform the choir of St. John's Lutheran Church choir in Northfield, Minnesota. By 1920, his St. Olaf Lutheran Choir toured nationwide and eventually epitomized a choral prototype through his publications, compositions, ideology, and methods, both original and derivative. Self-reliant and confident, Christiansen championed Russian choral literature, symphonic form for programming, and self-referential choral singing. His "inner choir" technique, "instrumental" tuning for choirs, and "conductorless" onset of tone were widely imitated. Spiritual beliefs undergirded his work. Originally inspired by Christiansen, Ohioan John Finley Williamson (1887-1964), a trained singer, cultivated choral tone by recontextualizing solo vocal Lamperti technique into choral methods. In 1920, he modeled his ensemble's results via national tours with his Dayton Westminster Choir. By 1926, he co-founded a choir school in a Dayton church where he implemented his theory of the choral rehearsal as a class voice lesson. His unorthodox tenets included his belief that vowels were controlled by volume and phrase conducting, that vowel color was dictated by overtones, and that a conflict existed between time beating and "rhythmic magic" (or "pace").