Harriett was involved with Daughters of the American Revolution. In 1895, Harriett formed a children's group of a similar vein called Children of the American Revolution. This group is still around today, and was organized "for the training of young people in true patriotism and love of country".
She loved travelling overseas, but spent many winters in California where the climate was more agreeable.
Alongside her writing career, Stone had a deep interest in historical homes and buildings and worked hard to preserve them. These include:
- The Wayside, where she lived with her family
- Orchard House, which belonged to the Alcott family and was next door to the Wayside
- Grapevine Cottage, where the Concord grape was first produced
- The Tolman House in Dorchester, Massachusetts built during the colonial period
In later years, Stone's daughter Margaret Lothrop championed to have her childhood home, The Wayside, declared a National Historic Landmark. It was made so in 1963.