Lewis was also part of trumpeter Miles Davis's "Birth of the Cool" sessions. While in Europe, Lewis received letters from Davis urging him to come back to the United States and collaborate with him, Gil Evans, Gerry Mulligan and others on the second session of "Birth of the Cool". From when he returned to the U.S. in 1948 through 1949, Lewis joined Davis's nonet and is considered "one of the more prolific arrangers with the 1949 Miles Davis Nonet". For the "Birth of the Cool" sessions, Lewis arranged "S'il Vous Plait", "Rouge", "Move" and "Budo".