It is a part of the municipality of Westland, and lies about 10 km (6.2 mi) south-west of The Hague.

The former municipality of Monster also included the villages Poeldijk and Ter Heijde.

Monster and Ter Heijde are located near the North Sea coast and have popular beaches.

In the 13th century a great deal of the Westland, Loosduinen and The Hague were administered by Monster.

Remains of the former glory can still be seen between The Hague and Monster at such estates as Ockenburgh, Bloemendaal, Solleveld and Langeveld.