Selkirkshire or the County of Selkirk is a historic county and registration county of Scotland. It borders Peeblesshire to the west, Midlothian to the north, Roxburghshire to the east, and Dumfriesshire to the south. It derives its name from its county town, the royal burgh of Selkirk. The county was historically also known as Ettrick Forest.

The shires of Scotland, or counties of Scotland, are historic subdivisions of Scotland established in the Middle Ages and used as administrative divisions until 1975. Originally established for judicial purposes, from the 17th century they started to be used for local administration purposes as well. The areas used for judicial functions (sheriffdoms) came to diverge from the shires, which ceased to be used for local government purposes after 1975 under the Local Government (Scotland) Act 1973.