The fossil site of Senèze, located in the Auvergne volcanic province of the French Massif Central, is well-Known for its mammalian fauna and its role as the reference locality for the Late Villafranchian time interval, an important phase in the evolution of the fauna of Europe. This site is a filled-in volcanic explosion-crater lake (maar) where fossils are found in volcano-clastic sediments interfingering with lacustrine deposits at the lake margin. The Senèze mammals are generally considered to date between 2.2-1.5 Ma, but some authors have argued that this assemblage is note unitary, rather composed of two associations of different age. Moreover, little has been published about the geological setting or the processes of site formation. Our Franco-American research project, co-directed by the three first authors since 2000, is re-examining Senèze for the first time in 60 years. The team effort has three main goals : 1) to clarify the local geology (stratigraphy, mineralogy) of this complex site and determine the taphonomic processes involved; 2) to utilize a combination of methods (ESR and argon dating ; tephrochronological and paleomagnetic correlation) to definitively establish the age of the site and its fauna; and 3) to collect additional mammalian fossils (especially of rare animals such as carnivores, primates and rodents) and samples of the non-mammalian biota, including vertebrates (e.g., birds and fisches), terrestrial and lacustrine invertebrates, pollen and diatoms from known points within the revised and dated stratigraphy. Several partial skeletons which appear devoid of carnivore disturbance have been recovered, and a new taphonomic hypothesis is proposed to explain this pattern. Some preliminary argon dates are presented for levels below the fossil mammals, while preliminary ESR and paleomagnetic results agree with an age broadly near 2 Ma. Pollen collected in situ and from coprolites allows a first step toward paleoenvironmental reconstruction