The Theory of Planned Behaviour (TPB) was used to investigate factors affecting the intention of citizens to donate money altruistically for sustainable rural development projects in Spain. To achieve this aim, individuals’ attitudes, subjective norms and perceived behavioural control have been considered; also, Azjen’s model was further extended to include additional elements: Moral norms, past behaviour, knowledge and some background factors. Respondents completed an online questionnaire assessing domains elaborated in the extended TPB model. Hierarchical multiple regression analysis revealed support for the model. Attitudes, injunctive norms, perceived behavioural control, moral norms, past behaviour, crowdfunding knowledge, age and employment condition were found to have positive and significant influence on intentions to donate. Theoretical and applied implications of the results are discussed, highlighting important considerations for public policy.