Prarthana Samaj, or the "Prayer Society" in Sanskrit, is a movement for religious and social reform in Maharashtra that is based on previous reform movements and traditions of Maharashtra. The direct antecedent of the Prarthana Samaj in Mumbai was the Paramahamsa Sabha, a secret society for the furtherance of liberal ideas that was formed in 1849 by Ram Balkrishna Jaykar and others in Mumbai. It was secret in order to avoid the anger of the powerful and orthodox fundamentals of society. Meetings were arranged for discussion, the singing of hymns, and the sharing of a communal meal prepared by a low-caste cook. Members of this community ate bread baked by Christians and drank water brought by Muslims.

Alike the Brahmo Samaj of Bengal, the Prarnatha Samaj represented an Indian response to European liberalism, including the principles of rational or theistic belief and social improvement. The members of the Prarthana Samaj followed the great religious tradition of the Maratha Sant Mat like Namdev, Tukaram and Ramdas(the guru of Shivaji). The Brahmo Samaj founders went through many world religions including ancient Vedic texts, which consequently were not accepted to be infallible or divine. Although the supporters of Prarthana Samaj were devoted theists, they also do not consider the Vedas as divine or perfect. They drew their sustenance from the Hindu scriptures and used the hymns of the old Marathi "poet-saints" in their prayers. Their ideas dated back to the devotional poems of the Vitthalas as part of the Vaishnava Bhakti devotional actions of the thirteenth century in southern Maharashtra. The Marathi poets had motivated a movement of conflict to the Mughals. But, beyond the religious concerns, the prime focus of the Prarnatha Samaj was on the social and cultural reform. The Prarthana Samaj critically looked into the relations between modern social and cultural systems and religious beliefs and thus gave importance to social reform as compared with the political alterations that were already initiated by the British government. Their all-inclusive reform movement has led many inspiring projects of cultural change and social improvement in Western India. Some of them include the improvement of the lot of women and dejected classes, an end to the caste system, elimination of child marriages and infanticide, educational opportunities for women, and remarriage of widows. Sir Ramakrishna Gopal Bhandarkar, Dr. Atmaram Pandurang, Narayan Chandavarkar and Justice Mahadev Govinda Ranade guided the successes of the community.

The Prarthana Samaj was first started in Bombay and was inspired by the Brahmo Samaj but is milder and less fundamental in its principles. Theistic worship came at the forefront. Many members hold the view that explicit beliefs and theological thought are not necessary for a boundless theistic movement. Prarthana Samaj believes that God is the creator of this universe and he is the only true God; there is no other God beside him. His worship alone shall lead to happiness in this world and the next. Love and reverence for him, praying and singing to him spiritually with these feelings is his true worship. To worship and pray to images and other idols is not a true mode of divine adoration. God does not incarnate himself and all men are His children; therefore they should have affection towards each other without distinction.

The doctrine of Prarthana Samaj was very similar to the Brahmo Samaj but with one significant difference. The Prarthana Samaj based its worship on the devotional poems of the Vitthalas, especially those of Tukaram. The Vitthalas or Varkari Panth, `pilgrim`s path,` is the sect of Vitthala, the Vaishnava bhakti devotional movement that rose in the thirteenth century and is centered on Pandharpur in the far south of Maharashtra.

In 1872 another great Brahmo personality, Pratap Chandra stayed for six months at the invitation of the Prarthana Samaj. During his visit there was a plan of making Prarthana Samaj to become a branch of Brahmo Samaj. This was prevented by Mahadeo Ranade pointing out the splits among the Brahmos of Bengal, which might be spread all across in Bombay. The Prarthana Samaj continued as an independent reform movement and this was the most important and well-organized movement of the time that was sponsored by leaders of society. The mildness of the Prarthana Samaj has meant that there have never been groups of missionaries as in the Brahmo Samaj. With only one or two missionaries the movement has not spread widely. However, the mildness of the Samaj has been attractive in the South, in Andhra Pradesh and Tamil Nadu, where the Prarthana Samaj is the most popular of the Samajs. The Samaj runs the Young Theists Union, the Postal Mission to send religious literature, the Subodh Patrika, night schools, and a Ladies Association.

In 1875 the Prarthana Samaj faced its first crisis and a resulting split among its members. Swami Dayananda Saraswati visited Gujarat and Maharashtra with the result that a new ideology of exposed truth, fundamental change, and open conflict provided a dramatically different species of religious movement. A section of the Prarthana Samaj membership was involved in Aryan ideology and was excited by Dayananda. They wanted to have the Prarthana Samaj openly reject all caste rules and restrictions. After extensive internal debate led by S. P. Kelkar, those who accepted Dayananda`s message broke away and founded the Brahmo Samaj of Bombay. Kelkar`s Brahmo Samaj however failed after eight years, and in 1882 he returned to the Prarthana Samaj and became one of their few missionaries.

Although the Prarthana Samaj does not support image-worship, in practice members follow the ceremonies of Hinduism though regarding them as of no religious importance. Thus Samaj members can still practice image-worship in their homes and be part of the caste system. It is said that the Prarthana Samaj pays adherence to Hinduism with a protest. However, their own services use hymns of the old Maratha poet-saints, especially Tukaram. The Prarthana Samaj maintained various institutions, namely a free reading room, a library, night schools for workers, and an orphanage in Pandharpur. After 1906, they also formed a Depressed Classes Mission of India under the leadership of Vithal Ramji Shinde. The establishment of this new society made a great difference in changing the religious and social life of Maharashtra.