In addition to usual Information and Communication Technology (ICT) devices, things are becoming “therapeutic” and can be dedicated to the specific needs of aging. However, because there is a diversity of senior impairments, one must diagnose needs, expectations, abilities or skills of seniors in order to provide the best adapted functions and usages. Moreover, these devices must be evaluated to determine their real potential and effectiveness. This paper discusses how to choose the best fit between a health technology and age-related deficits, and how we can assess the results of this fit. In this context we will use a tool and methodology called “Design for Adapted Devices” (i.e. DAD). DAD tries to develop adaptable systems based on the comprehensive diagnosis of human deficits and needs taking into account several dimensions of user diversity like skills and abilities (e.g. motor, cognitive skills, etc.), and measure deficits that “modulate users” performances (e.g. social support, experience, strategies, etc.). DAD gives prospective data to define future smart things and provides information about technology assessment.