The Orchestra of the Age of Enlightenment (OAE) is a British period instrument orchestra. The OAE is resident orchestra at Southbank Centre and Glyndebourne Festival Opera, Artistic Associate at Kings Place, and has its headquarters at Acland Burghley School. The leadership is rotated between four musicians: Matthew Truscott, Kati Debretzeni, Huw Daniel and Margaret Faultless.

A group of period instrumentalist players formed the OAE as a self-governing ensemble in 1986, and took its name from the historical period in the late 18th century where the core of its repertoire is based. The OAE does not have a principal conductor, but chooses conductors individually. The current Principal Artists are Sir Simon Rattle, Vladimir Jurowski, Iván Fischer, John Butt, Sir Mark Elder and András Schiff. William Christie is Emeritus Conductor, as were the late Frans Brüggen, Sir Roger Norrington, and Sir Charles Mackerras. Other conductors to have worked with the OAE at its invitation include Marin Alsop, Anu Tali, Yannick Nézet-Séguin, Sian Edwards, Edward Gardner, Suzi Digby, Robin Ticciati, Joanna Tomlinson, Philippe Herreweghe, Gustav Leonhardt, René Jacobs, Harry Bicket, Christopher Hogwood, Sigiswald Kuijken, Ivor Bolton, Monica Huggett, and Bruno Weil.

Sir Martin Smith was instrumental in establishing the OAE, securing crucial private funding for its inaugural work and serving on the Board for many years.  He is Life President of the orchestra.

The Ethos of the Orchestra is based on democracy; with the idea that the players are not simply technicians but also actively guide the artistic direction of the orchestra. When it began anyone who wanted to could become a member of the orchestra, although they would not necessarily be asked to play. Responsibility for concert planning is given to a Players' Artistic Committee (members of which also sit on the OAE Board of Directors) which is elected annually by the members. An early mission statement stated that the Orchestra of the Age of Enlightenment was to "Avoid the dangers implicit in:

The OAE's first concerts, in June 1986, were booked at Oxford's Town Hall and London's Queen Elizabeth Hall. Conducted by Sigiswald Kuijken, their first programme consisted of an Overture Suite by Telemann, Rameau's Suite from Dardanus, a symphony by Gossec and Haydn's Symphony No. 83. The founding leaders were Catherine Mackintosh, Elizabeth Wallfisch, Alison Bury and Margaret Faultless.

The OAE's current recurring season at the Southbank Centre in London includes concerts at the Queen Elizabeth Hall and Royal Festival Hall. In May 2006, the OAE started a series of informal late night concerts called "The Night Shift", which has twice been nominated for a Royal Philharmonic Society Award for audience development.

The OAE celebrated the 21st anniversary of its founding with a concert at the Royal Festival Hall on 30 June 2007, conducted by Norrington, Elder, Mackerras and Jurowski respectively.

In 2007 the OAE also won the RPS Ensemble award "for its stunning delivery of a breadth of repertoire, indefatigable advocacy of the interpretation of music played on original instruments and pioneering work in education and through a range of media – not to mention the artistry of its individual members in making each listening experience uniquely creative, engaging and thrilling."