 On 1 January 2019, the former commune Fourqueux was merged into Saint-Germain-en-Laye.<ref>Arrêté préfectoral 19 December 2018 </ref>

Saint Germain en Laye is connected to other communes by the Résalys bus network operated by Transdev Montesson-les-Rabeaux.Saint-Germain-en-Laye is served by Saint-Germain-en-Laye station on Paris RER line A.It is also served by two stations on the Transilien Paris – Saint-Lazare suburban rail line