This picture, presented to the National Gallery in 1847, and subsequently transferred to Tate in 1951, has for many years been among Reynolds's best known works. In the nineteenth century it was deeply admired and frequently copied, National Gallery records revealing that between its acquisition and the end of the century no fewer than 323 full-scale copies in oil were made.

The picture was not a commissioned portrait but a character study, or 'fancy picture', as the genre was known in the eighteenth century. The present title was not invented by Reynolds, but derives from an engraving of 1794, the second impression of which was inscribed 'The Age of Innocence'. Traditionally, it is has been thought that the picture was painted in 1788. However, it is very probably identifiable with a work exhibited by Reynolds at the Royal Academy in 1785, and entitled simply 'a little girl'. On 8 April 1785 The Morning Herald, previewing Reynolds's proposed exhibits for the forthcoming Royal Academy exhibition, noted: 'An Infant Girl, disposed on a grass plat in an easy attitude. The companion to it is a girl fondling a bird. These subjects are fancy studies of Sir Joshua's and do him honour'.