Society of Contemporary Music, held in Venice, Castelnuovo-Tedesco first met the Spanish guitarist Andrés Segovia. The meeting inspired Castelnuovo-Tedesco to write for the guitar, beginning with his Variazioni attraverso i secoli (Variations à travers les siècles) (Variations through the ages), Op. 71 (1932), and later his Guitar Concerto No. 1 (1939). All in all, he wrote almost one hundred compositions for this instrument, which earned him a reputation as one of the foremost composers for the guitar in the twentieth century. Some of them were written and dedicated to Segovia, who was an enthusiast of his style (Segovia called him an "incorruptible servant of artistic truth"). Even before the Italian government promulgated the Italian racial laws in late 1938, Castelnuovo-Tedesco was banned from the radio and performances of his work were cancelled. The new racial laws, however, convinced him that he should leave Italy. He wrote to Arturo Toscanini, the former musical director of La Scala, and violinist Jascha Heifetz, explaining his plight, and both responded with support. As an American citizen, Heifetz began paperwork to sponsor Castelnuovo-Tedesco as an immigrant in the United States. Castelnuovo-Tedesco left Italy in 1939, shortly before the outbreak of World War II. He wrote his Cello Concerto in F major, Op. 72, for Gregor Piatigorsky. It was premiered with the dedicatee under Arturo Toscanini in New York in 1935. For Piatigorsky he also wrote a Toccata (1935), and a piece called Greeting Card, Op. 170/3, based on the spelling of Piatigorsky's name. Like many artists who fled fascism, Castelnuovo-Tedesco ended up in Hollywood, where, with the help of Jascha Heifetz, he landed a contract with Metro-Goldwyn-Mayer as a film composer. Over the next fifteen years, he worked on scores for some 200 films there and at the other major film studios. Rita Hayworth hired him to write the music for The Loves of Carmen (1948), produced by Hayworth for her Beckworth Productions and released by Columbia Pictures. As a teacher, Castelnuovo-Tedesco had a significant influence on other major film composers, including Henry Mancini, Nelson Riddle, Herman Stein and André Previn. Jerry Goldsmith, Marty Paich and John Williams were all his pupils, as was Scott Bradley, who studied privately with him while both were on staff at MGM. He also maintained close contact with composer Robert Strassburg. His relationship to Hollywood was ambiguous: later in life he downplayed the influence that it had on his