With demographic changes and the growing numbers of older people living alone, concerns have been raised about the care of the ageing population. Increasingly, developments in technology are being seen as the solution to these concerns. For those who do not see themselves as old or frail enough to require personal care provision, and who prefer to maintain their identity as autonomous and independent individuals, the development of assistive technologies such as ambient home monitoring systems is one answer. However, this involves careful negotiations with older people's understandings of safety and privacy, and their experiences and relationships with technology, their carers and relevant service-providers. In two trials of a home monitoring system funded by the United Kingdom Technology Strategy Board, older people were interviewed pre-trial and post-trial about their perspectives on these issues. This paper presents a conceptual analysis of the qualitative data using a sociological framework of trust that considers habitual action, and relationships with kin and with wider institutions. The research found that older people's habits and norms do not need to be disrupted by the ambient system. What was of more importance was relationships between the older person and her or his ‘monitor’ based on trust, as well as institutional providers who need to instil or earn trust.