Diana Thewlis holds degrees in Advertising Art and Illustration. She free-lanced and worked full-time for various companies as a graphic artist, designer, letterer, fashion illustrator, and technical illustrator before becoming a full-time free-lance illustrator in 1980. Although her clients have covered a broad range of genres, her emphasis was on illustrating for children, primarily in the educational arena. She began teaching at the Academy of Art University in 1992. In 2013 she retired as a contract illustrator and part-time professor.
She is currently painting and drawing regularly, exploring her muse and new arenas. Diana paints all subject matter, although the majority of her works are figurative. Her primary media are watercolor and mixed media. Pen and ink, acrylics, collage, as well as soft and oil pastels complete her repertoire.
She has participated in several shows, won numerous awards, and has judged many shows for The Academy of Art University and numerous art associations.
Her work resides in the Air Force Art Collection and in various private collections around the world.