Westmorland (/ˈwɛstmərlənd/, formerly also spelt Westmoreland) is an area of North West England which was historically a county. The area included part of the Lake District and the southern Vale of Eden, and its inhabitants were known as Westmerians.

The county had an administrative function from the 12th century until 1974, when it was subsumed into Cumbria together with Cumberland, the Sedbergh area of Yorkshire, and the Furness area of Lancashire. It gives its name to the Westmorland and Furness unitary authority area, which covers a larger area than the historic county.

At the beginning of the 10th century a large part of modern day Cumbria was part of the Kingdom of Strathclyde, and was known as "Scottish Cumberland". The Rere Cross was ordered by Edmund I (r.939–946) to serve as a boundary marker between England and Scotland ("Scottish Cumberland").

At the time of Domesday Book in 1086, the county did not exist; half was considered to form part of Yorkshire and the other half part of Scotland. Before 1226, the Barony of Kendal was part of the Honour of Lancaster while the Barony of Westmorland was part of the Earldom of Carlisle, the latter became Cumberland and was part of Scotland at times.

Both baronies became a single county of Westmorland in 1226/7. Neighbouring Lancashire was also formed at this time. Appleby was the historic county town, having been chartered in 1179. It was a parliamentary borough from 1295–1832, and incorporated by letters patent in 1574.

Westmorland bordered Cumberland to the north, County Durham and Yorkshire to the east, and Lancashire to the south and west. Windermere formed part of the western border with Lancashire north of the sands, and Ullswater part of the border with Cumberland. The highest point of the county is Helvellyn, at 3,117 feet (950 metres). According to the 1831 census the county covered an area of 485,990 acres (196,670 hectares).

Westmorland was subdivided into the two baronies of Westmorland (or sometimes Appleby) and Kendal. As with Cumberland, Durham and Northumberland it was divided into wards. The baronies were each further subdivided into two wards:

In 1889, under the Local Government Act 1888, a county council was created for Westmorland, taking functions from the quarter sessions. The county council was based at the County Hall in Kendal, although the assizes were held in the Shire Hall in the historic county town of Appleby. Kendal had been chartered as a municipal borough in 1835, Appleby in 1885. The county had no county boroughs throughout its history, so the administrative county, the area under the control of the county council, was coterminous with the geographic county.