The evidence base for lifestyle monitoring is relatively weak, even though there are significant numbers of commercial installations around the world. We conducted a literature review to summarize the current position with regard to lifestyle monitoring based on sensors in the home. In total, 74 papers met the inclusion criteria. Only four papers reported trials involving 20 or more subjects, with a further 21 papers reporting trials involving one or more subjects. Most papers (n = 49) were concerned with technology development. Motion detection was the most common of the technologies employed, followed by door and electrical appliance usage. The predominant monitoring strategy was that of detecting changes in activity. However, little attention has been given to determining when or how changes in the profile of activity should be used to raise a call for assistance from a health or care professional. Lifestyle monitoring remains a relatively immature research area in which there is little detailed understanding of how to provide comprehensive and effective systems.