Humanitarian aid professionals frequently encounter situations in which one is conscious of the morally appropriate action but cannot take it because of institutional obstacles. Dilemmas like this are likely to result in a specific kind of stress reaction at the individual level, labeled as moral stress. In our study, 16 individuals working with international humanitarian aid and rescue operations participated in semistructured interviews, analyzed in accordance with a grounded theory approach. A theoretical model of ethical decision making from a moral (...) stress perspective was developed. The practical implications of the study are discussed. (shrink)