This study compared the help-eliciting capacity of 4 helping conditions. Within each condition a male confederate dropped in the path of an oncoming pedestrian either 5 books, 5 coins, a glove (unwittingly), or a book (while the confederate was on crutches). The percentage of subjects helping ranged from 3 to 100, depending on the condition. The results were interpreted as supporting the proposition that the probability that a person will offer assistance to a stranger in need of help approaches certainty under conditions of low costs and high dependency and high personal responsibility. In addition, there was no evidence of sex differences in help-giving; however, there was some evidence that children are more likely to help than adults. (Author)