Series 1 contains material pertaining to Kastle's early works in the 1940s. There are many musical compositions for the piano as well as music for a ballet. There are also multiple sonatas, preludes and fugues in this series as well.
Series 2 contains compositions Kastle wrote based on poems, such as those written by Emily Dickinson, Robert Frost, and A.E. Houseman. This also contains compositions for Mass, which was aired on Public Television in 1978.
Series 3 contains musical scores for many of Kastle's works. The series is broken down into subseries according to the six major instrumental compositions found in this collection. Each subseries usually contains a manuscript score, while some contain a published score. Subseries 3, Concerto No. 1, is the only subseries to contain Musicians' parts and tissues of parts.
The fourth series contains musical and vocal compostions for the operas written by Kastle. Like Series 3, Series 4 is also broken down into subseries according to major works. Most of the subseries contain Masters of Parts, Blues of Parts, or Tissues of Parts as well as Orchestral Scores or Vocal Scores. A large amount of the material found in this series is undated.
This series contains manuscripts for the multiple screenplays that Kastle wrote during his lifetime. As previously stated, some were produced while others were not. This series contains both handwritten drafts and typed manuscripts.
