Another of Hill's concerns was the availability of open spaces for poor people. She campaigned against development on existing suburban woodlands, and helped to save London's Hampstead Heath and Parliament Hill Fields from being built on. She was one of the three founders of the National Trust, set up to preserve places of historic interest or natural beauty for the enjoyment of the British public. She was a founder member of the Charity Organisation Society (now the charity Family Action) which organised charitable grants and pioneered a home-visiting service that formed the basis for modern social work. She was a member of the Royal Commission on the Poor Laws in 1905.