The electronic structure of the I-3(-) molecular anion and its photoproducts I-2(-), I-2, and I-3 were studied. Ab initio calculations were carried out using the multireference configuration interaction (MRCI) method for the valence electrons together with a relativistic effective core potential. The ab initio wave functions were also used to compute some spin-orbit coupling matrix elements, as well as approximate valence bond wave functions, used as guidelines in the construction of a 108-state diatomics in molecule (DIM) description of the electronic structure of I-3(-). In the DIM model, spin-orbit coupling was introduced as a sum of atomic operators. For I-2(-) the ab initio and the DIM ground-state potentials show excellent agreement with the experimental results. The results for I-2 are also in very good agreement with experimental data. For I-3(-), the MRCI calculations give a very good description of the spectroscopic constants and agree with the vertical excitation energies, provided spin-orbit coupling is included. The DIM description fails both quantitively by leading to erroneous spectroscopic constants, and qualitatively by not even reproducing the MRCI ordering of the excited-states. The failure of the DIM is attributed to the omission of ionic states. The overall qualitative picture of the excited-state potentials shows a maze of dense avoided crossings which means that all energetically allowed photoproducts will be present in the experiment. The ground electronic state of I-3 was calculated to be a collinear and centrosymmetric (2)Pi (u,3/2). The collinear state is stabilized by spin-orbit coupling relative to a bent configuration. Calculated vertical transition energies from the ground to low-lying excited states of the radical are in excellent agreement with the experimental data. The spin-orbit assignment of these states is provided.