Christensen served as associate director of the San Francisco Ballet in 1949, and was co-director in 1951 with his brother Willam. He served as director from 1952–1984. Christensen transformed the San Francisco Ballet to an internationally recognized
neoclassical company. Although he joined the San Francisco Ballet in 1949, Christensen continued to act as ballet master for the
New York City Ballet until 1950. After becoming co-director of the San Francisco company in 1951, he kept a good relationship between it and the New York City Ballet. In 1952, on his brother Willam's departure to establish the ballet program at the
University of Utah, Lew became the director of the company. He choreographed over 110 works for the San Francisco Ballet. He brought impressive choreography from Balanchine to the company. With Christensen as director, San Francisco Ballet made its first tours nationally and internationally and received much acclaim. == Personal life ==