Recent advances in educational and training technology are offering an increasing number of innovative and promising learning environments including three-dimensional and two-dimensional virtual worlds as well as computer simulations. These environments differ a lot as to both their technological sophistication and to the types of skills taught, varying for example from immersive 3D environments of high-fidelity to simulations of complex relational situations, for the learning of "soft skills" of growing strategic interest to enterprises such as leadership, customer service, coaching, selling etc. The learning potential of virtual training relies on the possibility for learners to make a number of significant first-person experiences and to fail in a safe and protected environment. In order to be effective, the experience should seem real and engaging to participants, as "if they were in there": they should feel (emotionally and cognitively) present in the situation. The goal of this chapter is to investigate the relationships existing among the factors that are crucial to the emergence of a sense of presence in virtual training environments. This exploration aims at outlining a possible model of presence in virtual learning environments, trying to define on the one hand the key factors conveying it in training contexts and on the other hand how the sense of presence contributes to enhance learning efficacy and to support following transfer of knowledge and skills.