The initial dynamics after excitation to the S-1 state of tetraphenylethylene is studied using femtosecond pump-probe spectroscopy. From the rapid spectral changes during the first few hundred femtoseconds, we conclude that a fast ethylenic twisting motion occurs in the excited state within this time period. We observe a coherent oscillation, building up during the twist and then decaying rapidly, which we ascribe to the concerted response of the phenyl rings to the release of steric strain. The subsequent full geometric relaxation of the distorted molecule is hindered by collisions with the solvent molecules and takes several picoseconds, dependent on solvent viscosity. The motions involved in this relaxation process govern the formation of a charge-separated (cs) state and the equilibrium that is established between this cs state and the nonpolar excited state.