Stevenson was the only son of Thomas Stevenson, a prosperous civil engineer, and Margaret Isabella Balfour. He attended Edinburgh Academy and other schools before, at 17, entering Edinburgh University, where he was expected to prepare himself for the family profession of lighthouse engineering. But Stevenson had no desire to be an engineer, and he eventually agreed with his father, as a compromise, to prepare instead for the Scottish bar.
In 1873 he met Fanny Sitwell, soon Stevenson was deeply in love, and on his return to Edinburgh he wrote her a series of letters in which he played the part first of lover, then of worshipper, then of son. One of the several names by which Stevenson addressed her in these letters was "Claire".
Later in 1873 Stevenson suffered severe respiratory illness and was sent to the French. Stevenson was frequently abroad, most often in France. Two of his journeys produced An Inland Voyage (1878) and Travels with a Donkey in the Cévennes (1879). His career as a writer developed slowly. His essays appeared in Macmillan's Magazine, and his first contribution (on Victor Hugo) appeared in "The Cornhill Magazine".
Later, in Edinburgh, he was introduced to the writer W.E. Henley. The two became warm friends and were to remain so until 1888, when a letter from Henley to Stevenson containing a deliberately implied accusation of dishonesty against the latter's wife precipitated a quarrel that Henley, jealous and embittered, perpetuated after his friend's death in a venomous review of a biography of Stevenson.
In 1876 Stevenson met Fanny Vandegrift Osbourne, an American lady separated from her husband, and the two fell in love. Stevenson's parents' horror at their son's involvement with a married woman subsided somewhat when she returned to California in 1878, but it revived with greater force when Stevenson decided to join her in August 1879. Stevenson reached California ill and penniless (the record of his arduous journey appeared later in The Amateur Emigrant, 1895, and Across the Plains, 1892). His adventures, culminated in marriage to Fanny Osbourne early in 1880. After a honeymoon by an abandoned silver mine (recorded in The Silverado Squatters, 1883) the couple sailed for Scotland to achieve reconciliation with the Stevensons.

Soon after his return, Stevenson, accompanied by his wife and his stepson, Lloyd Osbourne, went, on medical advice (he had tuberculosis), to Davos, Switz.
There, Stevenson embarked on Treasure Island (begun as a game with Lloyd), which started as a serial, under the title The Sea-Cook, in October 1881.Then started on Prince Otto (1885), a more complex but less successful work.
In 1881 Stevenson published Virginibus Puerisque, his first collection of essays, most of which had appeared in The Cornhill. In April 1882 he left Davos; but a stay in the Scottish Highlands, while it resulted in two of his finest short stories, "Thrawn Janet" and "The Merry Men", and in September he went to the south of France. There Stevenson was happy and worked well. He revised Prince Otto, worked on A Child's Garden of Verses (first called Penny Whistles), and began The Black Arrow: A Tale of the Two Roses (1888).
The threat of a cholera epidemic drove the Stevensons back to England. They lived at Bournemouth from September 1884 until July 1887, but his frequent bouts of dangerous illness proved conclusively that the British climate was not for him. There he got to know and love the American novelist Henry James. There he revised A Child's Garden (first published in 1885) and wrote "Markheim," Kidnapped, and Strange Case of Dr. Jekyll and Mr. Hyde. It was Dr. Jekyll--both moral allegory and thriller--that established his reputation with the ordinary reader.
In August 1887, still in search of health, Stevenson set out for America with his wife, mother, and stepson. On arriving in New York, he found himself famous, with editors and publishers offering lucrative contracts. He stayed for a while in the Adirondack Mountains, where he wrote essays for Scribner's and began The Master of Ballantrae.

In June 1888 Stevenson, accompanied by his family, sailed from San Francisco. He was to spend the rest of his life in the South Seas.
As a result, his writings on the South Seas (In the South Seas, 1896; A Footnote to History, 1892) are admirably pungent and perceptive.
He died suddenly of a cerebral haemorrhage, not of the long-feared tuberculosis. His work during those years was moving toward a new maturity. Catriona (U.S. title, David Balfour, 1893), The Ebb-Tide (1894) (it was a complete reworking of a first draft by Lloyd Osbourne), Weir of Hermiston (1896), the unfinished masterpiece on which he was working on the day of his death. "The Beach of Falesá" (first published 1892; included in Island Night's Entertainments, 1893),

New Arabian Nights, 2 vol. (1882; the stories in vol. 1 appeared as Latter-Day Arabian Nights, 1878); Treasure Island (1883); More New Arabian Nights (1885); Prince Otto (1885); Strange Case of Dr. Jekyll and Mr. Hyde (1886); Kidnapped (1886); The Merry Men and Other Tales and Fables (1887), including "Thrawn Janet" and "Olalla"; The Black Arrow: A Tale of the Two Roses (1888); The Master of Ballantrae (1889); Catriona (1893); The Ebb-Tide, (1894); Weir of Hermiston (unfinished 1896); St. Ives (completed by Sir Arthur Quiller-Couch, pseudonym "Q") (1897).

An Inland Voyage (1878); Travels with a Donkey in the Cévennes (1879); Virginibus Puerisque (1881), Familiar Studies of Men and Books (1882); Memories and Portraits (1887), 16 essays; Across the Plains (1892), 12 essays; Vailima Letters, (1895); From Scotland to Silverado, ed. By J.D. Hart (1966).

A Child's Garden of Verses (1885); Underwoods (1887), 38 poems in English, 16 in Scots; Ballads (1890); Songs of Travel and Other Verses (1896). Collected Poems, ed. By J. Adam Smith, 2nd ed. (1971).