"Smart" materialsmaterials that respond to a stimulus or their environment to produce a dynamic and reversible change in critical propertieshave enabled progress in many areas, including display technologies, drug delivery, and self-healing materials for coating applications, among others. Many of the current examples of smart materials are biomimetic, since nature employs and depends on dynamic and rapid switching for critical functions such as vision, camouflage, and ion channel regulation. Despite progress in designing smart materials and surfaces, much work is still needed in this area to increase their implementation in useful applications. In this Perspective, the challenges and outlook in this field are highlighted, including the work of Balazs and co-workers found in this issue of ACS Nano.