Healthcare professionals currently lack the means to gather unbiased and quantitative multi-modal data about the long-term behaviors of patients in their home environments. SPHERE is a multi-modal platform of non-medical sensors for behavior monitoring in residential environments that aims to overcome this major limitation of healthcare provision by using the inherently cost-efficient and scalable technologies of the Internet of Things (IoT). One of SPHERE's key tasks is to help bring the next-generation low-power wireless networking and sensing technologies from the lab to the field by applying them in real-world environments. In this article we describe the highlights of SPHERE's system requirements, architecture, practical challenges, and design and deployment lessons learned. By leveraging novel IoT technologies such as the IEEE 802.15.4 network protocol, SPHERE has achieved successful initial deployments in 12 volunteer houses at the time of this writing.