One of the central issues in Westermarck’s ethics concerns the emotional foundations of moral norms. This chapter focuses on one part of this larger topic by looking at Westermarck’s sympathy-based theory on the origin and maintenance of moral norms that he interpreted as human universals. These concern murder and infliction of physical harm, theft, offences against honour and reputation, lying and cheating, failure to reciprocate altruistic action, the neglect of basic parental duties, and self-neglect and self-harm. In addition, sympathy is involved in influencing the widespread moral norms concerning the treatment of the dead and practices regulating human behaviour towards gods. Besides moral universals, Westermarck’s key objective was to explore variations in moral practices across cultures and to identify their underlying causes. In his view, the variations in moral beliefs can be traced to three interrelated sources, which may be broadly described as environmental, cognitive and emotional.