In August 1724, he purchased the stock and household goods of William Taylor, the first publisher of Robinson Crusoe, for £2282 9s 6d.

[citation needed] Longman entered into partnership with his father-in-law, Osborn, who held one-sixth of the shares in Ephraim Chambers's Cyclopaedia (1728).

In 1799, Longman purchased the copyright of Lindley Murray's English Grammar, which had an annual sale of about 50000 copies.

[1] In the following year, Richmal Mangnall's Historical and Miscellaneous Questions for the Use of Young People was purchased, and went through 84 editions by 1857.

[3] About 1800 he also purchased the copyright of Southey's Joan of Arc and Wordsworth's Lyrical Ballads, from Joseph Cottle of Bristol.

He published the works of Wordsworth, Coleridge, Southey and Scott, and acted as London agent for the Edinburgh Review, which was started in 1802.

[4] In 1814 arrangements were made with Thomas Moore for the publication of Laila Rookh, for which he was paid £3000; and when Archibald Constable failed in 1826, Longmans became the proprietors of the Edinburgh Review.

Their first success was the publication of Macaulay's Lays of Ancient Rome, which was followed in 1841 by the issue of the first two volumes of his History of England, which after a few years had a sale of 40000 copies.

Thomas Longman edited a beautifully illustrated edition of the New Testament, and William Longman was the author of several important books, among them a History of the Three Cathedrals dedicated to St Paul (1869) and a work on the History of the Life and Times of Edward III (1873).