Isabelle Rainsberger served in the Army Nurses Corps during World War II. Later she served as a Nurse in the Veteran's Administation Hospital in Dayton, Ohio.

Isabelle was a strong supporter of missionary work. She was one of the state side team of people supporting the medical work of Dorothy Thomas in what was then the Belgian Congo. When Isabelle and Dorothy both retired they bought a home together in Florida and continued raising funds for mission work.