The photochemistry of the oxygen dimer was investigated using the technique of resonance-enhanced multiphoton ionization. Ozone and oxygen atoms were produced following photolysis of oxygen dimers at wavelengths between 251 and 266 nm, which are below the energy needed to break the O-2 bond at 242 nm. The production of ozone in the upper stratosphere following (O-2)(2) photolysis was evaluated, with less than or equal to 1% of the daily ozone at 40 km being produced from this mechanism.