The reward-cost model of helping behavior in emergency situations suggests that the probability that an observer will help a victim depends, in part, on the relative strength of the rewards and costs of providing help. Factors that influence willingness to help in non-emergency situations were examined using descriptions of situations in which a person asked for different kinds of help. A sample of 132 college students indicated the amount of help they would provide in each situation and rated the perceived costs and rewards of providing help. Helping in the non-emergency situations was negatively related to the costs of helping and positively related to the rewards for helping and to personality differences in altruism, while controlling for social desirability bias in each case. In addition, highly altruistic persons viewed identical situations as more rewarding and less costly than persons low in altruism. The findings suggest that individual differences in helping behavior may reflect variations in the perception of social situations. (Author/JAC)