Global demographic changes and the increasing participation of senior citizens in leisure tourism activities have prompted governments and tourism providers in many developed regions to identify seniors as a priority market. Yet the lack of theory related to senior tourism poses a major hurdle to continued research in this field, especially with regard to the application of evolving age theories. Few studies analyse the relevance or motivations of senior tourists. Therefore, this study investigates the tourism behaviour of Spanish senior travellers, including both their motivations and their tendency to travel. To develop a theoretical framework, this article relies on three theories to explicate the travel behaviour of senior citizens: lifecycle theory, continuity theory and generational theory.