In 1887, Edward Hegler started Open Court Publishing, a publishing company dedicated to providing the public with excellent literature on the topics of philosophy, science, and religion, from the ground floor of his mansion. He then hired Dr. Paul Carus, a scholar and writer from Germany, to be the publishing company's managing editor. Paul and Mary fell in love and were married a year later. Paul continued to run the publishing company from the mansion while Mary ran the zinc business, until Paul's death in 1919, after which Mary ran both companies. The zinc manufacturing company died a few decades after Mary's death, and the publishing company left the Hegeler Carus Mansion, but the Hegeler and Carus families' businesses live on in other forms. Edward Carus, a son of Paul and Mary, founded Carus Chemical Company, which manufactures potassium permanganate, in 1915, and the company is still run by the Carus family. Open Court Publishing turned into the Carus Publishing Company, which publishes fourteen children's magazines, including the famous Cricket magazine.
The mansion is now a museum that guests can visit year round. Visitors can tour the main rooms of the mansion, which have been restored to a late 19th-century look, and they can also buy something at the gift shop. Concerts and lectures are held on the mansion grounds, well as within the home, and there are events throughout the year, such as Moonlight Tours in October and Victorian era Christmas decorations in December.