Kit-Cat Club (act. 1696–1720), was, at its height in the first decade of the eighteenth century, Britain's pre-eminent political club and a leading promoter and sponsor of the whig party and its advocacy of contract theories of government, low-church interests, and the rights of religious nonconformists. Whig politics was further shaped by a commitment to political liberty and an appreciation of the economic and social benefits of commerce and city life which gained momentum in the wake of the revolution of 1688, and which became a prominent theme in the Kit-Cat's patronage of new forms of popular cultural politics.

The precise dates of the Kit-Cat Club's existence remain unclear, and its origins have been traced to the immediate aftermath of the revolution of 1688 (J. Oldmixon) or, more commonly, to the mid- to late 1690s. The club's early obscurity suggests its origin as a private aristocratic circle which initially met informally in the wake of William III's accession and gradually came to prominence as it grew in size and influence during the late 1690s and early 1700s. The absence of minute-books means that there is no fixed membership list for the club. The majority of sources estimate that between forty-eight and fifty-five individuals were at one time Kit-Cats, though the society's longevity ensured that not all were affiliated at any one point, and that founding members such as the poet and politician Charles Sackville, sixth earl of Dorset, died before the height of its achievement.

More clear is that the club developed from a friendship between the bookseller Jacob Tonson the elder and a London pastry cook, Christopher Cat. A celebrated publisher of John Dryden, Tonson had by the 1680s become intimate with the leading members of the whig literary establishment, among them the earl of Dorset. According to Ned Ward's history of the club, Cat encouraged Tonson to hold meetings with Dorset and others at his premises—the Cat and Fiddle, Gray's Inn Lane—luring members of the embryonic club with the quality of the refreshments he provided, in particular his mutton pies. Assured of this patronage Cat moved to a new shop near The Fountain tavern, Strand, which along with The Flask tavern, Hampstead, became the club's principal meeting place until, with a growing membership to accommodate, it relocated to Tonson's house at Barn Elms, Surrey, in 1703.

Explanations of the club's name are that it came either from the sign of Cat's shop, 'being the Cat and the Fiddle' (Ward, 361), or from the role played by Christopher's (Kit's) pies (cats) in drawing together the infant club:

Hence did th'Assembly's Title first arise,And Kit Cat Wits sprung first from Kits-Cats Pyes

Blackmore, 5though Joseph Addison, himself a leading member, claimed in The Spectator, no. 9 (10 March 1709), that ‘Kit-Cat’ was the full name of the mutton pie after which the society was named.

With Tonson as its founder and secretary, and Dorset its principal patron, the club's initial contributions to political debate were literary, with penmanship an essential attribute of the earliest Kit-Cats. In addition to Addison, literary members included the dramatists William Congreve and Sir John Vanbrugh, the political writers Sir Richard Steele and Arthur Maynwaring, the poets Sir Samuel Garth and William Walsh, and the wit and epicure Charles Dartiquenave. Led by Tonson, Congreve, and Vanbrugh, the club's then thirty members contributed about £100 each to the building of the Queen's Theatre in Haymarket, London, which opened in April 1705. Reflecting extra-parliamentary whig–tory rivalries, and their resulting social segregation, a section of the theatre's auditorium was reserved for exclusive Kit-Cat use. The Irish Jacobite, Charles Leslie, greeted the opening with a warning that 'The KIT-CAT Clubb is now grown Famous and Notorious, all over the Kingdom' (The Rehearsal, 12 May 1705, quoted in Allen, Kit-Cat Club, 57). However, an interest in the nation's cultural development meant that the club also sponsored a small number of tory poets, as well as being involved with commissioning for the Queen's Theatre until at least 1709.

Other members advanced the whig cause through the more direct route of parliamentary politics. It was as a political association that the club gained its greatest influence in the period of whig opposition between 1710 and 1714, serving as a social and financial network drawn from the three main, and most influential, elements of the party at Westminster. Thus aristocratic members within parliament comprised four of the party's five established leaders (the junto [see also Whig junto])—Thomas Wharton, first marquess of Wharton, John Somers, Baron Somers, Charles Montagu, earl of Halifax, and Charles Spencer, third earl of Sunderland—together with their associates: the army officer Charles Mohun, fourth Baron Mohun; the diplomat Charles Montagu, fourth earl of Manchester; the lawyer William Cowper, first Earl Cowper; and the courtiers Charles Howard, third earl of Carlisle, and William Cavendish, second duke of Devonshire. A second bloc within the party was formed by the great whig magnates, among them Charles Lennox, duke of Richmond and of Lennox; Thomas Pelham-Holles, first duke of Newcastle upon Tyne; Charles FitzRoy, second duke of Grafton; John Montagu, second duke of Montagu; and Charles Seymour, sixth duke of Somerset. A third group—principal among them Robert Walpole, later earl of Orford, William Pulteney, later earl of Bath, Edmund Dunch, and James Stanhope, later Earl Stanhope, as well as Maynwaring and Addison—sat in the Commons and included some of the most active and promising whigs in the lower house.

The absence of club minutes makes it difficult to trace the Kit-Cats' direct influence on whig strategy at Westminster and beyond. None the less certain policies have been attributed to the club. These included plans in 1711 to organize a popular demonstration against the tory government's moves for peace in the War of the Spanish Succession, and discussions in 1714 to defend the Hanoverian succession by military resistance to a projected Jacobite rising and French invasion following the imminent death of Queen Anne.

It was the Kit-Cats' dedication to the Hanoverian succession (a fundamental tenet of whig ideology under Anne) which later prompted Horace Walpole to state that the club's members, while 'generally mentioned as a set of Wits', were in reality 'the Patriots that saved Britain' (Walpole, Memoirs, 1.186). More generally the club's political activity bolstered party cohesion through an early but none the less strict whipping system which saw Lord Somerset 'expellet the Chitcat' in 1711 for defying party managers (Holmes, 298). During parliamentary recess discipline was maintained by the club's strong social presence and, more broadly, through its support of Addison and Steele (the latter himself an MP from 1713) whose dual involvement in parliament and Grub Street culture did much to publicize whig interests in pamphlet and periodical literature.

Through their periodicals, The Tatler (1709–10) and The Spectator (1711–12, 1714), Addison and Steele helped develop whiggery into a cultural ideal of as much consequence to the modern 'polite' gentleman as to the committed contract theorist or advocate of religious nonconformity. Kit-Cat members did not themselves always live up to these ideals. Drink was a staple of weekly meetings. In addition to the expected toasts to William III there were those to female favourites—including Anne, countess of Sunderland, and Henrietta, countess of Godolphin, daughters of another Kit-Cat, John Churchill, first duke of Marlborough—whose names, as was the club's custom, were engraved on drinking glasses. On other occasions, excessive drinking led to confrontation, as when, in 1708, Tonson identified Robert Walpole as 'the greatest villain' and Walpole responded with violence (Portland MSS, 4.493). Such episodes reflect perhaps the residual libertinism of some of its founders (notably Dorset when Lord Buckhurst), but under Addison's later influence the club became predominantly more civilized than sybaritic.

Civility was certainly the Kit-Cats' intended public image, which, then as now, was shaped most significantly by a set of forty-eight portraits of club affiliates commissioned by Tonson from the court painter, Sir Godfrey Kneller. Kneller produced his portraits at irregular intervals between the late 1690s and early 1720s (the earliest and latest dated works being 1702 and 1717), and from 1703 completed portraits were hung in a purpose-built gallery at Tonson's Barn Elms house.

In part Kneller's portraits followed the Renaissance ideals established in Britain by Sir Anthony Van Dyck: sitters facing the viewer with head slightly turned and right arm bent to meet a vertical support. But Kneller also developed the portrait genre to further the Kit-Cats' wider aim of promoting an urbane, and hence distinctly whig, culture of politeness. Using an intermediate canvas size of 36 inches by 28 inches (compared with the traditional bust, 30 inches by 25 inches, or three-quarter length, 50 inches by 40 inches), Kneller achieved greater intimacy in works which, by focusing on the upper body and face in life-size, better reflected each sitter's relaxed posture and, by inference, his approachable and accommodating character. Kneller's canvas—a size subsequently known as a ‘kitcat’—was used to record forty-seven single sitters, the exception being a late double portrait (c.1721) of Newcastle with his brother-in-law, Henry Clinton, seventh earl of Lincoln (1684–1728). Though predominantly of aristocratic subjects, the portraits and the club also included a significant minority of (then) commoners: in addition to those already mentioned, the army officer John Tidcomb, the politicians Spencer Compton, later earl of Wilmington, and Thomas Hopkins (c.1641–1720), the landowner John Dormer (1669–1719), and the diplomats Abraham Stanyan and George Stepney. Hung together the collection reiterated the Kit-Cats' principles of toleration, easiness, and gentility, identified by the club as society's reward for preserving the 1688 settlement in whig hands.

The accession of George I in 1714 meant that the Kit-Cat Club's principal political objective under Anne had been achieved. Thereafter it lost ground as the locus for whig party organization to the new Hanover Club, a more overtly political society dedicated to parliamentary management of government back-benchers from the Commons. By the early 1720s the club was effectively at an end. Its decline was due, partly, to the recent deaths of several of its junto leaders and other influential figures (for example, Addison in 1719), but owed more to its secretary Tonson's travels in France between 1718 and 1720. Writing to the publisher in 1725, Vanbrugh spoke of his hopes that remaining Kit-Cats might meet once more 'not as a club, but as old friends that have been of a club, and the best club that ever met' (The Complete Works of Sir John Vanbrugh, ed. B. Dobrée and G. Webb, 4 vols., 1927–8, 1.345; 4.167).

As a mark of gratitude for his secretaryship, each club member (starting with Somerset) had gifted his completed kitcat portrait to Tonson. The originals remained in the possession of the Tonson family until 1945, when they were acquired by the National Portrait Gallery, London; forty portraits now hang at the gallery and at Beningbrough Hall, York.

Other club members included: James Berkeley, third earl of Berkeley; Richard Boyle, second Viscount Shannon (c.1675?–1740); Algernon Capel, second earl of Essex (1670–1710); Charles Cornwallis, fourth Baron Cornwallis (1675–1722); James Dormer; Francis Godolphin, second earl of Godolphin; Richard Lumley, second earl of Scarborough (1688–1740); Evelyn Pierrepont, first duke of Kingston upon Hull; Lionel Sackville, first duke of Dorset; Richard Temple, first Viscount Cobham; and John Vaughan, third earl of Carbery.