Simulation holds enormous potential for medical education, where patient safety concerns have made practice on patients less acceptable. However, there is no unequivocal evidence of simulation training translating to improved performance in vivo. Therefore, the aim of this thesis is to add to the literature on simulation training by a) synthesising the current evidence on the effectiveness of simulation training in healthcare, b) investigating the effectiveness of different ‘doses’ of mannequin training in learning laryngeal mask airway placement and c) assessing the effectiveness of a simulation course on managing life threatening illness. This thesis has added to the literature in the field of medical education a review of reviews of the evidence regarding the effectiveness of simulation training in medicine and surgery, and two RCTs evaluating different simulation training courses. The review of reviews highlighted that simulation training can be effective, but there was little consistent evidence across tasks or types of simulator. The two RCTs reported nil results, reinforcing that simulation alone is insufficient to ensure effectiveness. These results highlight the importance of recognising when simulation training is appropriate, how simulation interacts with other elements of a training programme and how the simulation can be made maximally effective.