Prarthana Samaj, or "Prayer Society" in Sanskrit, was a movement for religious and social reform in Bombay based on earlier reform movements. Prarthana Samaj was founded by Atmaram Pandurang in 1867 when Kesab Chandra sen visited Maharashtra, with an aim to make people believe in one God and worship only one God. It became popular after Mahadev Govind Ranade joined. The main reformers were the intellectuals who advocated reforms of the social system of the Hindus.It was spread to the southern India by noted Telugu reformer and writer, Kandukuri Veeresalingam.
The movement was started as a movement for religious and social reform in Maharashtra and can be seen much more alike Brahmo Samaj. The precursor of the Prarthana Samaj in Mumbai was the Paramahamsa Sabha, a secret society for the furtherance of liberal ideas by Ram Balkrishna Jaykar and others in Mumbai. It was secret in order to avoid the wrath of the powerful and orthodox elements.
By comparison with the parallel Brahmo Samaj of Bengal, and the ideals of rational or theistic belief and social reform, the Prarthana Samaj(ists) were followers of the great religious tradition of the Marathi Sant Mat like Namdev, Tukaram. The Brahmo Samaj founders examined many world religions, including ancient Vedic texts, which subsequently were not accepted to be infallible or divine. Although the adherents of Prarthana Samaj were devoted theists, they also did not regard the Vedas as divine or infallible. They drew their nourishment from the Hindu scriptures and used the hymns of the old Marathi "poet-saints" in their prayers. Their ideas trace back to the devotional poems of the Vitthalas as part of the Vaishnava bhakti devotional movements of the thirteenth century in southern Maharashtra. The Marathi poets had inspired a movement of resistance to the Mughals. But, beyond religious concerns, the primary focus of the Prarthana Samaj was on social and cultural reform.
Prarthana Samaj critically examined the relations between contemporary social and cultural systems and religious beliefs and gave priority to social reform as compared with the political changes already initiated by the British government. Their comprehensive reform movement has led many impressive projects of cultural change and social reform in Western India, such as the improvement of the lot of women and depressed classes, an end to the caste system, abolition of child marriages and infanticide, educational opportunities for women, and remarriage of widows. Its success was guided by Sir Ramakrishna Gopal Bhandarkar, a noted Sanskrit scholar, Dr. Atmaram Pandurang, Narayan Chandavarkar, and Justice Mahadev Govinda Ranade. Ranade emphasized that "the reformer must attempt to deal with the whole man and not to carry out reform on one side only".