The articles in this special section focus on system requirements for security, privacy, and trust for the Internet of Things (IoT). IoT has huge potential to push monitoring, computing, and communication deeply into the home, the workplace, medicine, manufacturing, and critical infrastructure. This increased capability offers the hope that urban settings can be transformed in various ways through the innovative deployment of IoT devices. Driven by a decline in the cost of sensors, many cities have adapted a plan to transition services toward being a fully smart city by implementing real-time data-driven management services across urban systems, including efficiently managing water, energy, waste, policing, and transportation among other citywide services. Cities continue to attract new people and the United Nations (UN) estimates that by 2030, more than 60% of the global population will live in large cities.1 With nearly 38 million people, Tokyo tops the UN’s ranking of most populous cities, followed by Delhi, Shanghai, Mexico City, São Paulo, and Mumbai.