Hamonic+Masson & Associés is led by Gaëlle Hamonic, Jean-Christophe Masson and, since 2014, Marie-Agnès de Bailliencourt. Founded in 1997, the agency was nominated for the Mies van der Rohe award in 2001 and was awarded the Nouveaux Albums de la Jeune Architecture (Naja) in 2002.

In 2003 the agency came to the attention of the wider public with the design of the Maison Métal,
exhibited in the Parc de la Villette, a project that placed it at the confluence of art and architecture. In 2008 it was appointed co-curator of the French Pavilion at the Venice Biennale. In 2012, the agency was awarded the special AMO Saint-Gobain prize for its 62-home project on rue Villiot in Paris XII.