This thesis was motivated by a wish to understand the slow response to HIV/AIDS and so seeks to address the questions of why and when people help others. The questions are important, as typically it is others who decide who among those most in need receive help. To narrow the focus to motives of help, the discussions consider the helping of distant others, as typically such actions do not involve material gain to the helper. Related literature exists on charitable behaviour but tends towards a marketing approach. This limits its use in providing specific input regarding motives. The economics literature is far more specific and a review identifies four groups of models. These models have a number of weaknesses, so an alternative is suggested: the balance model, and a responsibility formulation, is proposed for this and existing models, which, it is argued, assist in addressing the questions. Following on from the identification and development of alternative theoretical frameworks, these options are taken through a process of attrition. They are contrasted with evidence and theory from the psychology literature - first on helping and then on harming. This exercise suggests the relative strength of the balance model and the maintenance of a responsible self-image model. Both deal well with explaining how help differs according to context and how individuals might avoid or deliberately misinterpret information. The balance model is used to examine individual helping behaviour, by way of an economic experiment. The model is then expanded to consider the social context, which allows for the consideration of the HIV response. The theoretical discussions and the experimental results suggest that individuals feel a responsibility to help. They can, however, try to avoid information which may prompt such feelings and manipulate themselves to reduce the pressure such feelings place on them to help.