Mary Carpenter was the daughter of a Unitarian Minister, Lant Carpenter, whose family moved to Bristol in 1817. In 1833 the Brahmo Samaj Reformer, Raja Rammohun Ray, visited Bristol and was an important influence upon Mary Carpenter, encouraging an interest in India. Carpenter moved into Red House Lodge in Bristol in 1858 and entertained a number of Indian visitors to Britain, including Satyendranath Tagore, the elder brother of Rabindranath, who arrived in Britain in 1863 and was the first Indian to join the ICS through the competitive ranks, his companion Manomohun Ghose, Joguth Chunder Gangooly, an ordained minister from Boston, and Rakhal Das Haldar who visited Britain for education in the 1860s.
Mary Carpenter visited India four times, the first was in 1866 where she was accompanied by Manomohun Ghose, returning to India after having been called to the Bar, and the daughter of Dr Goodeve Chuckerbutty from Calcutta who had been sent to England for education. Her first port-of-call was to Satyendranath Tagore in Bombay, and on this trip she met Sasipada Banerji who was to return the visit in 1871.
During her third visit to India in 1870, Keshub Chunder Sen discussed with Carpenter the idea of forming an association in Britain. Sen visited her in Bristol in June 1870 and in September 1870, Mary Carpenter inaugurated the Bristol Indian Association. This Association was subsequently renamed the National Indian Association and was designed to promote social reform (particulary female education) in India and provide a meeting place for Indian visitors to Britain. In January 1871, Carpenter began producing the Journal of the National Indian Association. After her death in 1877, the headquarters of the Association were transferred to London.