The library is located in the north-west corner of the central block. It is clear from a plan in the fourth volume of Vitruvius Britannicus that James Paine had designated what became Adam’s library as a dressing room, with an adjacent family bedchamber at the centre of the north front (which later became the billiard room). However, on Paine’s departure, the room remained a shell.

In 1764, prior to inheriting from his father, the 5th Baronet had already begun to make plans for fitting up a library in this as yet untouched room. This was the first room on which Adam worked at Nostell, and appears to have been of considerable importance to the 5th Baronet as an emblem of learning and taste. This much can be seen from an exaggerated version of Adam’s library at Nostell bring used as the backdrop for the 5th Baronet and Sabine’s famous portrait by Hugh Douglas Hamilton of 1767. Moreover, the room was located adjacent to the room which Adam designated as the 5th Baronet’s dressing room (later the billiard room) resulting in an elegant, masculine suite.

Adam’s drawings for the interior of the library were sent to Nostell in August 1766, with Benjamin Ware, Adam’s clerk of works. A drawing for a mirror frame – now lost – was also sent in June 1767, and there is a preliminary design showing laid out wall elevations in Robert Adam’s own hand, and datable to 1766, within the private collection of Lord St Oswald.

The plasterwork in the library was executed by Joseph Rose (junior) in 1766-67 at a cost of £169.17s.2d, and medallions for the walls and ceiling were painted by Antonio Zucchi, and dispatched from London in August 1767. The books which first populated the shelves were purchased in bulk and sent to Nostell in July 1767, although those for the sham shelves on the doors were produced by Thomas Chippendale.

The walls and inbuilt bookshelves were repainted by George Guest in 1783-95 with a wood grain effect which masks Adam’s lighter colour scheme, and survives in situ.