Research has shown that emotions are directly linked to cognition and there is a strong correlation between affect and learning. This notion along with recent technological advancements has prompted researchers from many disciplines to turn their attention toward adding an affective component to human-computer dialog. This chapter discusses emotion assessment methods, recent empirical research related to examining students´ affective states in entertainment and educational games, and conceptual, methodological, and technological issues associated with developing emotion recognition models. An overview of emotion recognition research suggests that there is little consensus on what emotions should be measured and how to do it. Moreover, it is still not clear how emotions affect human learning and performance.