The Protocol Analysis of the design process is a very recent and very promising research field. It is believed that good application-oriented developments are possible mainly in the tutorial field (ITS). The research conducted up to now has primarily dealt with the study of the design process. On the contrary, we propose an investigation experiment on the knowledge structures relative to the use of the episodic memory in the architectural design. The proposed experiment concerns the monitoring of the cognitive processes utilised by tutors and students in a brief, but yet complete design session. The results have lead to a synthetic model (computational model) of the adopted knowledge structures, and to a complete index system oriented and organised according to semantic fields. The application of the synthetic model to the design process analysis of students and tutors enabled the definition of the different utilisation strategies of episodic memory to be defined. The results obtained will make up the structure of a tutorial program for the architectural design.