This experiment integrated information from two areas of research-patient p
erception and belief in a just world (BJW)-that have heretofore offered rel
atively separate insights into when people will help others. We provided pa
rticipants an actual opportunity to help a target medical patient and attem
pted to demonstrate that volunteering is affected by both characteristics o
f the patient (perceived responsibility for disease onset) and characterist
ics of the perceiver (BJW). Participants were significantly more likely to
help an individual portrayed as not responsible for disease onset, and help
ing was most pronounced in participants who held a high BJW. Our findings s
uggest an interactive model of patient perception and helping behavior in w
hich characteristics of the patient interact with characteristics of the pe
rceiver.