The use of mock conferences (MCs) to prepare student interpreters for future professional careers has been repeatedly mentioned by interpreting studies scholars, yet the systematic design of MCs and their teaching effects are under-researched. This article justifies the use of MCs as a situated approach in interpreting teaching and describes the principles and procedures of MC design before reporting on a case study of their teaching effects. Data were collected through web-based questionnaires from 15 second-year graduate trainees of interpreting. The trainees rated MCs as good, beneficial and stimulating experiences, and their ratings were positively correlated to frequencies of their interpreting at MCs. Findings indicate that skills concerning professionalism, psychological competence, strategic competence and many other non-linguistic dimensions may be better acquired at MCs than in traditional interpreting classes. Those areas of competences concur with the pedagogical advantages of MCs reported by trainees. The trainees suggested improving the authenticity and pedagogical progression, and videotaping their performances for reflection, with a view to better design of the MCs in which they had been involved. This study has significant implications for preparing trainee interpreters for their future professional life through the use of MCs.