In this paper we describe a "Train the Tutor" programme (TtT) for developing the metacognitive skills, facilitator skills, and tutor skills of students in a problem based learning (PBL) context. The purpose of the programme was to train 2nd and 3rd year undergraduate students in psychology to become effective PBL tutors for "freshmen" (1st year psychology students). Based on the 3C3R concept of Hung (2006), various instructional problems have been designed and used in a 6 steps training programme. The programme has been evaluated both in a formative and summative approach through a quasi-experimental control group design with pre- and post-measurements before and after the training programme. The study was conducted as part of a curriculum re-design for promoting problem based learning in psychology courses for undergraduate students in a university of applied science. The results indicate the importance of metacognitive skills of the tutor for effectively facilitating the learning process in a PBL context.