Abstract: This paper will explore the impacts of multiple home ownership and use of multiple residences on cities and regions in affluent societies. Trends of increasing affluence and mobility expose the shortcomings of conventional planning methods based on measures such as ‘usual’ residence. The paper considers ideas about ‘sea change’ and ‘tree change’, which figure prominently in the Australian media, and the impacts of multiple dwelling ownership, mobility and migration between metropolitan and non-metropolitan areas. Affluent incomers have both positive and negative impacts on many coastal and country areas. These processes are of interest to a range of policy makers as well as many citizens active in local community organizations. Comparative evidence will be introduced from Ireland and Victoria and related to an international literature on mobility, lifestyles, life courses, absentee home owners, household consumption, investment strategies, and public policy debates. The authors have conducted research separately on aspects of the ownership of second homes (‘holiday homes’) in Australia and Ireland and are currently undertaking further work on changing patterns of mobility, the impact of these changes on communities and public policy issues especially strategic land-use planning and intergovernmental fiscal relations.