Introduction Simulations have been used as early as 1910 as a means to train both individuals and teams to reduce errors and improve safety (Fowlkes, Dwyer, Oser 1998:209-221). Commercial aviation and the military have invested heavily in the use of simulation- based training because it offers a realistic, safe, cost-effective, and flexible environment in which to learn the requisite competencies for the job ( Salas 2001: 641-674). Given its professed success in these areas, the use and application of simulations as a training tool has spread to a number of other domains, such as business, education, and medicine (Jacobs, Dempsey 1993: 197-228). Although the popularity of simulation-based training has grown during the past decade, using simulation as a part of training is not a panacea. A review of the team training literature in health care, which we conducted in 2004 (Salas 1999: 123-161), showed, for example, that simulation-based training is used to improve team performance (Howard 1992: 763–770). However, it appeared that simulation-based training programs early on either focused on the engineering component of training (that is, the simulator itself) or took a more balanced approach in which simulation is studied in the context of a learning methodology. Yet research indicates that simply adding simulation to training does not make it more effective nor will it guarantee that trainees learn more, better, or the right things (Salas 1999: 123-161). Rather, simulation-based training must be designed and delivered on the basis of what we know about the science of training and learning (Salas, Cannon-Bowers 2001: 471–499). Simulation-based training provides opportunities for trainees to develop requisite competencies through practice in a simulated environment that is representative of actual operational conditions; trainees receive feedback related to specific events that occur during training (Oser et al. 1999: 175–202). There is a wide array of simulation types that can be used to train teams ( Beaubien, Baker 2004: 51–56). Simulations can range from low-fidelity role playing exercises (for example, an event/scenario is reenacted) to part task trainers to high-fidelity full-motion simulations. Validated simulation promotes greater depth of understanding and higher levels of retention while promoting the development of stronger critical thinking and analytical skills and generate enthusiasm for learning. The aim of this paper is to describe the effects of the use of simulation exercises on teamwork. Observations regarding the historical developments are linked to the current state of the literature and the implications of these observations for future direction of simulation literature are briefly discussed. The research will look at learning and motivational theories, and how theories impact on knowledge gained during the simulation exercise and its effect on teamwork. The pedagogical value of validated simulation will be analyzed and learning opportunities and factors influencing and affecting teamwork will be outlined. Attention to transferable skills or ‘deep learning’ such as working and relating to others, communication, problem solving has intensified and will be referred to