TELEMAC-MASCARET is an integrated suite of solvers for use in the field of free-surface flow. Having been used in the context of many studies throughout the world, it has become one of the major standards in its field. TELEMAC-MASCARET is managed by a consortium of core organisations: Artelia (France), BundesAnstalt für Wasserbau (BAW, Germany), Centre d’Etudes Techniques Maritimes et Fluviales (CETMEF, France), Daresbury Laboratory (United Kingdom), Electricité de France R&D (EDF, France), and HR Wallingford (United Kingdom). TELEMAC-MASCARET is used by most partners for dimensioning and impact studies, where safety is prevailing and, for this reason, reliability, validation and a worldwide recognition of our tools are of utmost importance. As a consequence and to improve the access to TELEMAC-MASCARET for the whole community of consultants and researchers, the choice of open source has been made. Anyone can thus take advantage of TELEMAC-MASCARET and assess its performances, and will find necessary resources on this website. However the quality of assistance, maintenance and hotline support are also very important to professional users, and a special effort has been made to offer alternatively a broad range of fee-paying services. INSTALLATION : Information on how to install TELEMAC-MASCARET can be found on http://www.opentelemac.org