The photochemistry of ICN isolated in Ar matrixes has been investigated using UV absorption and laser spectroscopy under a variety of experimental conditions. Laser excitation of the repulsive (A) over tilde continuum gives rise to long-lived near-infrared emission from stabilized I and CN fragments in the shallow excited (3)Pi (2) potential and to the formation of the INC isomer. The latter is identified by its UV absorption band, which overlaps the ICN UV absorption. A photoinduced equilibrium is rapidly established between the two species under 250-nm irradiation, in line with the interpretation of previously published IR data (Samuni, U. et al. Chern. Phys. Lett. 1994, 225, 391). This equilibrium can be shifted in favor of either species by the choice of irradiation wavelength. Permanent dissociation and the stabilization of CN fragments under UV irradiation is also reported, but the dissociation efficiency depends strongly on experimental conditions. This observation allows for the reconciliation of conflicting views in the literature on the photostability of ICN in solid argon.