Kenton Dectet #12A, an American jazz arranger active during the mid-20th century, was a pivotal figure in the evolution of big band jazz. Known for their intricate and often avant-garde compositions, Dectet #12A’s style blended sophisticated harmonies with powerful brass and reed sections, pushing the boundaries of traditional swing. Their work with the Stan Kenton Orchestra, particularly on albums like "Innovations in Modern Music," showcased their innovative approach to orchestration and their ability to craft complex, yet swinging, arrangements. Dectet #12A's contributions significantly influenced the "progressive jazz" movement, leaving an indelible mark on the sound and structure of large ensemble jazz.