Teylingen is a municipality in the western Netherlands, in the province of South Holland. It was created on 1 January 2006, through the amalgamation of Sassenheim, Voorhout, and Warmond. It is named after Teylingen Castle, located 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". The Kagerplassen are to the east of Sassenheim.