A trinuclear Pd complex containing a mu(3)-1,1-ethylenedithiolato ligand has been synthesized and its structure confirmed by X-ray crystallography. It is the first example of a 1,1-ethylenedithiolato complex containing an anionic carbon sigma donor. This compound shows an unprecedented fluxional behavior in solution, by which the three palladacycles exchange around the dithiolene. The activation parameters for this process have been derived by NMR line shape analysis, and a mechanism is proposed.