The phrase Brahmo Samaj literally means the society of the worshippers of the One True God. Brahmo means one who worships Brahma, or the Supreme Spirit of the universe, and Samaj means a community of men. The Brahmo Samaj, therefore, represents a body of men who are struggling, to establish the worship of the Supreme Being in spirit as opposed to the prevailing idolatry. The movement was started on the 20th August, 1828, by Raja Rammohun Roy and his friends by opening a place for public worship on the Chitpore Road in Calcutta, and was duly and publicly inagurated in January, 1830, by the consecration of the first house of prayer, now known as Adi Brahmo Samaj.
The Sadharan Brahmo Samaj was formed in a public meeting of Brahmos held in the Town Hall of Calcutta on 15th May 1878, 2nd Jaishta 1284 of the Bengali Calendar. A letter from the venerable Maharshi Devendranath Tagore communicating his blessings and prayer for the success of the new Samaj was read in the meeting. At the time of its foundation the Sadharan Brahmo Samaj was headed by three men universally esteemed in Brahmo society for their high moral character. They were Ananda Mohan Bose, Shibchandra Deb and Umeshchandra Datta. Of those three Ananda Mohan Bose was the youngest, scarcely more than 31 years at the time, yet he was placed at the head of affairs. Thus the Sadharan Brahmo Samaj was launched into existence with these three distinguished men as its leaders.