 The Latin etymology of “supererogation” is paying out more than is due (super-erogare), and the term first appears in the Latin version of the New Testament in the parable of the Good Samaritan. Although we often believe that Good Samaritanism is praiseworthy and non-obligatory at the same time, philosophical reflection raises the question whether there can be any morally good actions that are not morally required, and even if there are such actions, how come they are optional or supererogatory. Thus, the substantial literature on supererogation since the 1960s demonstrates that even though the class of actions beyond duty is relatively small and the philosophical attention paid to it is only recent, the status of supererogation in ethical theory is important in exposing deep problems about the nature of duty and its limits, the relationship between duty and value, the role of ideals and excuses in ethical judgment, the nature of moral reasons, and the connection between actions and virtue. Supererogation raises interesting problems both on the meta-ethical level of deontic logic and on the normative level of the justification of moral demands.