The extent of cure for epoxy resin (BADGE) with a small excess of amine hardener (DDM, 4 w/o) was determined by assay of the epoxy groups using near infrared spectroscopy. The effect of cure time at 100 degrees C and postcure time at 180 degrees C has been investigated. For the lower temperature cures the room temperature density, rho(rt), increased with time, reaching a maximum at X(e) = 0.87, and then decreased with extended cure times. For postcure, there was a monotonic decrease in rho(rt) that was unrelated to the extent of cure. There was an approximate linear relationship between glass transition temperature and ln(t), which increased even when essentially all of the epoxy groups had reacted, that is X(e) similar to 0.99.