This paper reports an investigation of the stability and dissociation dynamics of the low-lying singlet and triplet states of atone (O-3) using coincident photoelectron and photofragment translational spectroscopy. These experiments provide an upper limit of 0.5 mu s for the lifetime of the low-lying excited states of O-3. The (3)A(2) and B-3(2) states dissociate with nearly all available energy appearing in translation. Dissociation of the higher-lying B-3(1) and (1)A(2) states produces rotationally and possibly vibrationally excited O-2 products. The product translational energy distributions indicate that the B-3(1) state dissociates nonadiabatically to ground-state O(P-3) + O-2((3) Sigma(g)(-)) products.