A brief discussion about the Time-Temperature-Transformation (TTT) diagram is presented. Using diamino diphenylsulfone-cured diglycidyl bisphenol A as a representative example, its TTT diagram is completed by including the thermal degradation. The theoretical diagram as obtained from the kinetics of curing and thermal degradation is compared with experimental data. The agreement is good, slight deviations are observed only in the time to vitrify above 150degreesC and the maximum available glass temperature, which is due to side reactions and onset of thermal degradation during curing. (C) 2003 Wiley Periodicals, Inc.