Nelson Smock Riddle Jr. was an American arranger, composer, bandleader and orchestrator whose career stretched from the late 1940s to the mid-1980s. He worked with many vocalists at Capitol Records, including Frank Sinatra, Ella Fitzgerald, Nat King Cole, Judy Garland, Dean Martin, Peggy Lee, Johnny Mathis, Rosemary Clooney and Keely Smith. He scored and arranged music for many films and television shows, earning an Academy Award and three Grammy Awards. He found commercial and critical success with a new generation in the 1980s, in a trio of Platinum albums with Linda Ronstadt.

In music, an arrangement is a musical adaptation of an existing composition. Differences from the original composition may include reharmonization, melodic paraphrasing, orchestration, or formal development. Arranging differs from orchestration in that the latter process is limited to the assignment of notes to instruments for performance by an orchestra, concert band, or other musical ensemble. Arranging "involves adding compositional techniques, such as new thematic material for introductions, transitions, or modulations, and endings. Arranging is the art of giving an existing melody musical variety". In jazz, a memorized (unwritten) arrangement of a new or pre-existing composition is known as a head arrangement.