Reviewed current explanations of altruism and found them unsatisfactory for developing a general theory of altruistic behavior. Based on a social-psychological model of behavioral intention, an informational approach to altruism was tested in the context of blood-donating behavior. Beliefs, attitudes, and intentions regarding donating blood were obtained from 270 college students. The significant correlation between donating behavior and intentions to donate ( r = .59) was mediated by ability and reliance upon other persons or events. There were significant multiple correlations between the model's components and intentions to donate blood for both a 2-component version of the model ( R = .64) and an alternative 3-component version emphasizing moral obligation ( R = .69). Both versions substantially mediated the influence of 10 other variables related to intentions to donate. Subsequent analysis revealed that beliefs regarding the negative consequences of donating were those differentiating intenders from nonintenders. Implications of the informational approach for a reconceptualization of the act of helping are discussed. (36 ref) (PsycINFO Database Record (c) 2016 APA, all rights reserved)