 Diemer's compositional style over the years has varied from tonal to atonal, from traditional to experimental.She has written works for non-professional and professional performers, originally under the "Gebrauchsmusik" philosophy, but has produced many works, particularly for keyboard, that are difficult and challenging.The latter category includes her "Fantasy" for piano; Seven Etudes for piano; Homage to Cowell, Cage, Crumb, and Czerny for two pianos; Variations for Piano Four Hands (Homage to Ravel, Schoenberg, and May Aufderheide); Four Biblical Settings for organ, Concerto for Organ ("Alaska"); and many psalm setting collections.