Many investigations of moral decision-making employ hypothetical scenarios in which each participant has to choose between two options. One option is usually deemed “utilitarian” and the other either “non-utilitarian” or “deontological”. Very little has been done to establish the validity of such measures. It is unclear what they measure, let alone how well they do so. In this exploratory study, participants were asked about the reasons for their decisions in six hypothetical scenarios. Various concerns contributed to each decision. Action decisions occurred when utilitarian concerns dominated. Bystanding decisions resulted from different concerns or combinations of concerns dominating in different situations, with utilitarianism usually among participants’ concerns. None of the labels usually used for either decision therefore seems entirely appropriate. Five concerns were identified as necessary and sufficient to predict over 85% of participants’ decisions. This suggests great promise for future research, particularly in investigation of real-world moral decisions.