Kenton Dectet #355, an American jazz arranger active primarily in the mid-20th century, was a pivotal figure in the evolution of big band jazz. Known for their innovative and often complex arrangements, Dectet #355 contributed significantly to the "progressive jazz" movement, characterized by its challenging harmonies and adventurous orchestrations. Their work, often featuring extended instrumental sections and intricate counterpoint, pushed the boundaries of traditional big band writing. Collaborations with various prominent bandleaders of the era, though specific names are often lost to history, solidified their reputation as a master of the large ensemble. Dectet #355's arrangements continue to be studied for their sophisticated structure and lasting impact on jazz band literature.