Cognitive or motor function decline are major causes of loss of independent living among the aged. Several methods employing ubiquitous or unobtrusive technologies have been proposed for application toward in-home assessment to identify clinically meaningful change. Most attempts at multidimensional home monitoring have been on a limited scale. This has been the result of both technical and clinical research challenges in applying and more importantly testing the efficacy of such methods on a community-wide scale. We designed and implemented a system for application to a community based clinical trial of the efficacy of a basic sensor net (motion and contact sensors, RF location systems, and personal home computer interaction) to be studied in 300 homes of independent seniors. In this manuscript we describe a protocol to ensure several key outcomes: facilitation of recruitment and enrollment, customized training of elders for in-home computer use, optimized sensor net installation, tracking of subject status and linkage to study management software to enable on-line, real-time testing and trouble-shooting with seniors. The methodology suggests that large-scale unobtrusive in-home assessment is feasible for research needed to establish the efficacy of such systems for detection of cognitive decline and related conditions of aging.