Teylingen is a municipality in the province of South Holland, the Netherlands. It was created on January 1, 2006, through the amalgamation of Sassenheim, Voorhout, and Warmond. It is named after Castle Teylingen, located on the northern edge of Sassenheim, in Voorhout.
The municipality is bordered by Noordwijkerhout and Lisse to the north, Haarlemmermeer and Alkemade to the east, Leiderdorp and Leiden to the south, and Oegstgeest and Katwijk to the west. It is located in an area called the "Dune and Bulb Region" (Duin- en Bollenstreek). The Kaag Lakes (Kagerplassen) lie just to the east of Sassenheim.