論文アブストラクト：Despite a proliferation of research in the use of ICTs to support active and healthy ageing, few have considered the privacy and security concerns particular to the elderly. We investigated the appropriation of tablet devices and a neighborhood portal as well as emerging privacy and security issues through ethnographic and action research in a long-term participatory design (PD) project with elderly participants. We discuss two major themes: a) the tensions related to perceived digital threats and the social pressures of online disclosure to the social environment; and b) the relation of these issues to the ICT appropriation process and the referring challenges we encountered. We argue that there is a need to understand the interleaving of physical and virtual habitats, the various ways resulting in discomfort and the senior citizens' actions -- which at first glance appear contradictory. We consider the implications of the issues observed for examining privacy and security concerns more broadly as well as discussing implications for the design of the portal and the shaping of social measures for appropriation support.