A widely discussed attribute in the economic literature is the prevalence of self-interest. In this article we seek to analyze the concept of altruism from the economic perspective and from the general perspective of human action. We endeavour to clarify the relative confusion around it and to analyze its relation with charity and volunteering. Then, we go further and analyse what is causing such actions. Based on this, we attempt to find out whether the pro-social actions can be considered an effect of self-interest, or, conversely, of altruism