A kinetic investigation of the photobromination of ethylene has led to results which are in general consistent with the earlier work of Schumacher et al. The existence of an induced oxidation reaction was demonstrated in mixtures containing traces of oxygen, which is a very strong inhibitor of the ethylene-bromine chain reaction.The relative quantum yields of the photobromination reaction were measured at six wavelengths using narrow pass Baird interference filters. The quantum yields were shown to be independent of wavelength between the limits of 4800 and 6800A. Radiation of 7150A wavelength is absorbed but is totally ineffective photochemically. These results were interpreted with the aid of spectroscopic information to mean that the photochemically effective transitions of bromine molecules in radiation of wavelengths longer than the convergence limit, 5107A, lead to the continum of the 3π1u state, which then dissociates in one elementary act to form two normal atoms. It is unnecessary to invoke the assumption of collisional dissociation of excited bromine molecules to explain their photochemical reactivity below the convergence limit.