Swami Vivekananda was born as Narendranath Dutta in Kolkata (Calcutta) on January 12, 1863. His father Viswanath Dutta, a man of liberal and progressive outlook, was an attorney at Calcutta High Court. His mother Bhuvaneshwari Devi was pious and had practiced austerities. It is believed that she had prayed to Vireshwar Shiva of Varanasi for a son. She reportedly had a dream in which Shiva rose from his meditation and said that he would be born as her son.
Young Narendranath's thinking and personality were highly influenced by his parents—he had his father’s rational mind and his mother’s religious inclination. From his mother he learnt the power of self-control and truly believed and practiced her teaching - "Remain pure all your life; guard your own honor and never transgress the honor of others. Be very tranquil, but when necessary, harden your heart." He was very adept at meditation and could enter the state of samadhi. It is alleged that he would see a light while falling asleep and he would have a vision of Buddha during his meditation.
Narendranath had varied interests and a wide range of scholarship in philosophy, religion, history, the social sciences, arts, literature, and other subjects. He was very interested in the Hindu scriptures like the Vedas, the Upanishads, the Bhagavad Gita, the Ramayana, the Mahabharata and the Puranas. He was also well versed in classical music, both vocal and instrumental and is said to have undergone training under two Ustads, Beni Gupta and Ahmad Khan. Since boyhood, he took an active interest in physical exercise, sports, and other organizational activities. Even when he was young, he questioned the validity of superstitious customs and discrimination based on caste, and refused to accept anything without rational proof and pragmatic test.
His family moved to Raipur in 1877. At that time there were no good schools in Raipur so he spent his time with his father and had discussions on spiritual topics. He learned Hindi there and for the first time the Question of existence of God came to his mind. The family returned to Calcutta in 1879 but the two years in Raipur were the turning point in his life. Raipur is sometimes termed as the "Spiritual Birthplace" of Swami Vivekananda. In the same year, he passed the entrance examination for Presidency College, Calcutta, entering it for a brief period and subsequently shifting to General Assembly's Institution. During the course of his study there, he studied western logic, western philosophy and history of European nations. In 1881 he passed the Fine Arts examination and in 1884 he passed the Bachelor of Arts.
Narendranath is said to have studied the writings of several Westerners like David Hume, Immanuel Kant, Johann Gottlieb Fichte, Auguste Comte, Herbert Spencer, John Stuart Mill, and Charles Darwin. He became fascinated with the Evolutionism of Herbert Spencer, and translated Spencer's book on Education into Bengali. Simultaneously, he was thoroughly acquainted with Indian Sanskrit scriptures and many Bengali works. According to his professors, student Narendranath was a prodigy.
Narendranath’s initial beliefs were shaped by Brahmo Samaj concepts, which include belief in a formless God and deprecation of the worship of idols. Not satisfied with his knowledge of Philosophy, he wondered if God and religion could be made a part of one's growing experiences and deeply internalized. He went about asking prominent residents of contemporary Calcutta whether they had come "face to face with God", but could not get answers which satisfied him. That was the point when he was first introduced to Ramakrishna Paramhansa. The introduction occurred in a literature class in General Assembly's Institution. Principal Reverend W. Hastie was lecturing on William Wordsworth's poem The Excursion and The Poet's nature-mysticism. In the course of explaining the word ‘trance’, Hastie told his students that if they wanted to know the real meaning of it, they should go to Ramakrishna of Dakshineswar. This prompted some of his students, including Narendranath to visit Ramakrishna Paramhansa.
Narendranath met Ramakrishna for the first time in November 1881. This proved to be a turning point in his life. He asked Paramhansa the same questions that he had been asking others - "Do you believe in God, Sir?" "Yes", he replied. "Can you prove it, Sir?" "Yes". "How?" "Because I see Him just as I see you here, only in a much intense way." This impressed young Narendranath and from that day he began to visit Ramakrishna Paramhansa regularly. Even though Narendra did not accept Ramakrishna as his guru initially, he was attracted by his personality. He initially looked upon Ramakrishna's visions as mere figments of imagination and hallucinations. And as a member of Brahmo Samaj, he revolted against idol worship and polytheism, and Ramakrishna's worship of Kali. He tested Ramakrishna, who never asked Narendra to abandon reason, and faced all of Narendra's arguments and examinations with patience—"Try to see the truth from all angles" was his reply. During the course of five years of his training under Ramakrishna, Narendra was transformed from a restless, puzzled, impatient youth to a mature man who was ready to renounce everything for the sake of God realization. In time, Narendra accepted Ramakrishna as his guru.
After the death of their master, Ramakrishna’s disciples, under the leadership of Vivekananda formed a fellowship at a half-ruined house at Baranagar near the river Ganga. This became the first building of the Ramakrishna Math. Vivekanada and other members of the Math often spent their time in meditation and discussing different philosophies and teachings of spiritual teachers including Ramakrishna, Adi Shankara, Ramanuja, and Jesus Christ. In the early part of 1887, Narendra and eight other disciples took formal monastic vows. Narendra took the name of Swami Bibidishanand. In January 1899, the Baranagar Math was shifted to a newly acquired plot of land at Belur in the district of Howrah, now famous as the Belur Math.
In 1888, Vivekananda left the math as a Parivrâjaka—the Hindu religious life of a wandering monk. His sole possessions were a kamandalu (water pot), staff, and his two favorite books—Bhagavad Gita and The Imitation of Christ. Narendranath travelled the length and breadth of India for five years, visiting important centers of learning, acquainting himself with the diverse religious traditions and different patterns of social life. He developed a sympathy for the suffering and poverty of the masses and resolved to uplift the nation. Living mainly on Bhiksha or alms, Vivekananda traveled mostly on foot and railway tickets bought by his admirers whom he met during the travels. During these travels he gained acquaintance and stayed with scholars, Dewans, Rajas and people from all walks of life—Hindus, Muslims, Christians, Pariahs (low caste workers) and Government officials. In Madurai, he met the Raja of Ramnad, Bhaskara Setupati. The Raja became the Swami's disciple and urged him to go to the Parliament of Religions at Chicago. With the aid of funds collected by his Madras disciples and Rajas of Mysore, Ramnad, Khetri, Dewans and other followers, Vivekananda left for Chicago on May 31, 1893. At this time, he assumed the name Vivekananda as suggested by Ajit Singh, the Maharaja of Khetri.
On his way to Chicago, Vivekananda visited Japan. He called the Japanese "one of the cleanest people on earth", and was impressed not only by neatness of their streets and dwellings but also by their movements, attitudes and gestures.
His journey to America took him through China, Canada and he arrived at Chicago in July 1893. But to his disappointment, he learnt that no one without credentials from a bonafide organization would be accepted as a delegate. He came in contact with Professor John Henry Wright of Harvard University. After inviting him to speak at Harvard and on learning from him of not having credentials to speak at the Parliament, Wright, "To ask for your credentials is like asking the sun to state its right to shine in the heavens." Wright then addressed a letter to the Chairman in charge of delegates writing, "Here is a man who is more learned than all of our learned professors put together." Parliament of Religions opened on September 11, 1893 at the Art Institute of Chicago. On this day Vivekananda gave his first brief address representing India and Hinduism. He bowed to Saraswati, the goddess of learning and began his speech with, "Sisters and brothers of America!" To these words he got a standing ovation from a crowd of seven thousand, which lasted for two minutes. When silence was restored, he began his address. He greeted the youngest of the nations in the name of "the most ancient order of monks in the world, the Vedic order of sannyasins, a religion which has taught the world both tolerance and universal acceptance." And quoted two illustrative passages in this regard, from the Bhagavad Gita—"As the different streams having their sources in different places all mingle their water in the sea. So, O Lord, the different paths which men take, through different tendencies, various though they appear, crooked or straight, all lead to Thee!" and "Whosoever comes to Me, through whatsoever form, I reach him; all men are struggling through paths that in the end lead to Me." Despite being a short speech, it voiced the spirit of the Parliament and its sense of universality. He spoke several more times at the Parliament on topics related to Hinduism and Buddhism. The parliament ended on September 27, 1893.