The ground- and excited-state properties of both gas phase and crystalline ruthenocene, Ru(cp)(2), are investigated using density functional theory. A symmetry-based technique is employed to calculate the energies of the multiplet splittings of the singly excited triplet states. For the crystalline system, a Buckingham potential is introduced to-describe the intermolecular interactions between a given Ru(cp)(2) molecule and its first shell of neighbors. The overall agreement between experimental and calculated ground- and excited-state properties is very good as far as absolute transition energies, the Stokes shift and the geometry of the excited states are concerned. An additional energy lowering in the B-3(2) component of the 5a(1)＇ --> 4e(1)" excited state is obtained when-the pseudolinear geometry of Ru(cp)(2) is relaxed along the low-frequency bending vibration.