The name "West Frisian" is only used outside the Netherlands, to distinguish this language from the closely related Frisian languages of Saterland Frisian and North Frisian spoken in Germany. Within the Netherlands, however, "West Frisian" refers to the West Frisian dialect of the Dutch language while the West Frisian language is almost always just called "Frisian" (in Dutch, Fries for the Frisian language and Westfries for the Dutch dialect.) The unambiguous name used for the West Frisian language by linguists in the Netherlands is Westerlauwers Fries (West Lauwers Frisian), the Lauwers being a border river that separates the Dutch provinces of Friesland and Groningen.
Most speakers of West Frisian live in the province of Friesland in the north of the Netherlands. Friesland has 643,000 inhabitants (2005), of whom 94% can understand spoken West Frisian, 74% can speak West Frisian, 75% can read West Frisian, and 27% can write it.
For over half of the inhabitants of the province of Friesland, 55% (c. 354,000 people), West Frisian is the native language. In the central east, West Frisian speakers spill over the province border, with some 4,000–6,000 of them actually living in the province of Groningen, in the triangular area of the villages Marum (West Frisian: Mearum), De Wilp (De Wylp), and Opende (De Grinzer Pein).
Also, many West Frisians have left their province in the last 60 years for more prosperous parts of the Netherlands. Therefore, possibly as many as 150,000 West Frisian speakers live in other Dutch provinces now, particularly in the urban agglomeration in the West, and in neighbouring Groningen and newly reclaimed Flevoland.