Saint-Germain-en-Laye is a commune in the Yvelines department in the Île-de-France in north-central France. It is located in the western suburbs of Paris, 19.1 km from the centre of Paris.
Inhabitants are called Saint-Germanois or Saint-Germinois. With its elegant tree-lined streets it is one of the more affluent suburbs of Paris, combining both high-end leisure spots and exclusive residential neighborhoods.
Saint-Germain-en-Laye is a sub-prefecture of the department. Because it includes the National Forest of Saint-Germain-en-Laye, it covers approximately 48 km², making it the largest commune in the Yvelines. It occupies a large loop of the Seine. Saint-Germain-en-Laye lies at one of the western termini of Line A of the RER.