Synthetic learning environments (SLEs) are often lauded for their ability to "motivate" trainees. However, little empirical evidence exists to support the popular claim that SLEs work because they are motivating. The reason for the lack of evidence supporting these claims lies in the often inadequate definition and measurement of the motivation experienced by these trainees. The present study makes a case for switching the focus from the nebulous term "motivation" to a more defined and measurable construct of training engagement which consists of one's personal investments of physical, cognitive, and emotional energies. An integrated SLE model is outlined and used as a theoretical explanation for why and how SLEs impact trainee engagement and training outcomes. Study One explores the antecedents of engagement among a sample of undergraduate students playing an educational videogame. Study Two examines the comparative levels of engagement between two training conditions (SLE and E-learning control group) and explores the mediating role of engagement in the relationship between SLE characteristics and training outcomes. Results indicate some support for the integrated SLE model demonstrating that the user judgments of meaningfulness and availability predict trainee engagement. Furthermore, trainees in the SLE condition seem to experience significantly higher levels of engagement compared to their control group counterparts. However, training outcomes were uninfluenced by training condition and engagement did not play a mediating role. Theoretical contributions, limitations and directions for future research are discussed.