The third year curriculum is structured separately for each student. There are ongoing opportunities for involvement in the three primary areas, but students either individually or in teams are also required to design and implement an independent conservation project, known as the thesis project. 

Some of the thesis projects occur within the Willowbank estate; others are at nearby sites. Special consideration is given to students who wish to work further afield. The School works with partners in the government sector, the private sector, and the academic sector to provide thesis project opportunities. 

The thesis projects are carefully documented as part of the ongoing evaluation. They become part of the student record of their Willowbank experience.

Graduates of the Diploma Program receive a Diploma in Heritage Conservation.