The relationship between the charge-recombination luminescence (CRL), weak Light emitted after u.v.-irradiation, and the development of properties during isothermal cure of epoxy/amine thermosetting resins was investigated. The changes in CRI, were compared with the transitions and changes in properties during cure as measured through dynamical mechanical analysis on separate samples cured in a rheometer. It was shown that gelation did not lead to any detectable change in CRL, whereas vitrification caused a pronounced increase in CRL. Measurements on fully cured systems at different temperatures confirmed that CRL only was observed when the system was in the glassy state. It was also found that the decay kinetics of the CRL signal were essentially independent of the temperature and of the degree of cure of the sample.