The dependence of cloud point at cure reaction-induced microphase separation (CRIMPS) on the reaction rate for multicomponent curing system (diepoxide + tertiary amine + additive) was studied. Three distinct regions associated with the change in the phase separation mechanism were detected. For additive concentrations far from the critical point in the phase diagram, the nucleation-and-growth mechanism with a low cure rate is found responsible for the phase separation. The mechanism of spinodal decomposition is typical of rapid cure. 120A mixed mechanism may be expected in case of intermediate cure rates. Near the critical additive concentration, the spinodal decomposition is realized at any cure rate. These conclusions are confirmed by the kinetic data obtained.