In the deep disposal of radioactive waste, the presence of several barriers serving complementary safety functions enhances confidence that the waste will be isolated and contained to protect human health and the environment. The barriers include the natural geological barrier and the engineered barrier system (EBS). The EBS itself may comprise a variety of sub-systems or components, such as the waste form, container, buffer, backfill, seals and plugs. These proceedings include the main findings and presented papers from the third NEA-EC workshop on engineered barrier systems, which focused on the role of EBS modelling in the safety case for deep disposal.  The workshop examined the modelling tools currently available and identified complex areas of assessment in which further dialogue is needed.