Empathy and sympathy are often used synonymously. Their conceptual overlap roots in the emotional turn of empathy research. Eventually, the emotion-based concept of empathy differed that much from the original "Einfühlung" that it got re-translated into German as "Empathie". In this chapter, Lux traces this emotional turn and the re-translation of the concept as "Empathie". In addition, she discusses methods used to measure emotions during empathy studies as well as the problems we face when we try to distinguish between empathy and sympathy in these research contexts. Finally, she concludes that a lack of distinction implicated in the measurements is one of the reasons that empathy has been strongly related to compassion, pro-social behavior and moral judgment originally associated with sympathy not empathy.