A swollen-state NMR method of rubber blend analysis has been used to study crosslinking in gum vulcanisates for cure times ranging from t30 to overcure. Natural rubber (NR) cis-poly(butadiene) (BR) and NR/BR blend vulcanisates cured with conventional and semi-EV sulphur systems based on three common sulphenamide accelerators were studied. For single polymers, maximum crosslink densities were similar for a given elastomer regardless of accelerator. The crosslink densities attained in the blend phases at maximum crosslinking were close to those expected from single polymer data, but the manner in which this was achieved was rather different from expected from cure behaviour of the single polymers. NR has a shorter scorch time than BR, but results indicate that in blend materials the BR phase begins curing before and at a much faster initial rate than NR. The cure rates are reserved as the cure progresses and the NR phase eventually attains the crosslinking levels expected from single polymer data.