Of the 35,000 printed books, many complement the Lambeth collections. Of the 57 incunabula, 51 are editions previously lacking at Lambeth. There are some 1,600 STC and 4,000 Wing books. Significant collections were donated or bequeathed to Sion College by Walter Travers, the puritan opponent of Richard Hooker; Henry Compton, bishop of London; John Lawson, M.D., brother-in-law of Archbishop Tenison; Thomas James (c.1650-1711), a London bookseller and mathematical printer to the King; and Richard Chiswell, bookseller in St. Paul's Churchyard, specialising in the works of Anglican divines. Other collections of note include the Jesuit Library seized at the time of the Popish Plot and transferred to Sion College in 1679, some 500 books from the Library of Archbishop Tenison, and the Port Royal Library, collected in the first half of the 19th century.
The extensive pamphlet collection includes some 3,700 items belonging to Edmund Gibson, bishop of London (1669-1748), 5,800 to John Russell, headmaster of the Charterhouse, and rector of St. Botolph without Bishopsgate (1787-1863), 1,600 to William Goode, dean of Ripon (1801-68), and 7,100 to William Scott, vicar of St. Olave, Jewry, London, (1801-68).