The spinning jenny is a multi-spindle spinning frame, and was one of the key developments in the industrialisation of textile manufacturing during the early Industrial Revolution. It was invented in 1764–1765 by James Hargreaves in Stanhill, Oswaldtwistle, Lancashire in England.

The device reduced the amount of work needed to produce cloth, with a worker able to work eight or more spools at once. This grew to 120 as technology advanced. The yarn produced by the jenny was not very strong until Richard Arkwright invented the water-powered water frame. The spinning jenny helped to start the factory system of cotton manufacturing.

The spinning jenny was invented by James Hargreaves. He was born in Oswaldtwistle, near Blackburn, around 1720. Blackburn was a town with a population of about 5,000, known for the production of "Blackburn greys," cloths of linen warp and cotton weft initially imported from India. They were usually sent to London to be printed.^{[citation needed]}

At the time, cotton yarn production could not keep up with demand of the textile industry, and Hargreaves spent some time considering how to improve the process. The flying shuttle (John Kay 1733) had increased yarn demand by the weavers by doubling their productivity, and now the spinning jenny could supply that demand by increasing the spinners' productivity even more. The machine produced coarse thread.

The idea was developed by Hargreaves as a metal frame with eight wooden spindles at one end. A set of eight rovings was attached to a beam on that frame. The rovings when extended passed through two horizontal bars of wood that could be clasped together. These bars could be drawn along the top of the frame by the spinner's left hand thus extending the thread. The spinner used their right hand to rapidly turn a wheel which caused all the spindles to revolve, and the thread to be spun. When the bars were returned, the thread wound onto the spindle. A pressing wire (faller) was used to guide the threads onto the right place on the spindle.

In the 17th century, England was famous for its woollen and worsted cloth. That industry was centred in the east and south in towns such as Norwich which jealously protected their product. Cotton processing was tiny: in 1701 only 1,985,868 pounds (900,775 kg) of cotton-wool was imported into England, and by 1730 this had fallen to 1,545,472 pounds (701,014 kg). This was due to commercial legislation (Calico Acts) to protect the woollen industry. Cheap calico prints, imported by the East India Company from Hindustan (as India was then called), became popular. In 1700 an Act of Parliament was passed to prevent the importation of dyed or printed calicoes from India, China or Persia. This caused grey cloth (calico that had not been finished – dyed or printed) to be imported instead, and these were printed in southern England with popular patterns. Lancashire businessmen produced grey cloth with linen warp and cotton weft, which they sent to London to be finished. Cotton-wool imports recovered and by 1720 were almost back to 1701 levels. Again the woollen manufacturers claimed this was taking jobs from workers in Coventry. Another law was passed, to fine anyone caught wearing printed or stained calico; muslins, neckcloths and fustians were exempted. It was this exemption that the Lancashire manufacturers exploited.

The use of coloured cotton weft, with linen warp was permitted in the 1736 Manchester Act. There now was an artificial demand for woven cloth. In 1764, 3,870,392 pounds (1,755,580 kg) of cotton-wool was imported.

In England, before canals, railways, and before the turnpikes, the only way to transport goods such as calicos, broadcloth or cotton-wool was by packhorse. Strings of packhorses travelled along a network of bridle paths. A merchant would be away from home most of the year, carrying his takings in cash in his saddlebag. Later a series of chapmen would work for the merchant, taking wares to wholesalers and clients in other towns, and with them would go sample books.