David Murakami-Wood holds a Canada Research Chair (Tier II) in Surveillance Studies at Queen’s University in Canada. His current research focuses on smart cities and he is the author of The Watched World: Globalization and Surveillance (2015, Rowman & Littlefield). Together with Mark Graham’s contribution in Chapter 28, this chapter has been excerpted from an important volume—Global City Challenges, edited by Michele Acuto and Wendy Steele in 2013. The book highlights new issues and insights concerning both the intellectual project of global city studies and the real developments in today’s global cities. In this contribution below, Murakami-Wood examines the proliferation of urban security policies and measures in the network of global cities with a case study of Rio de Janeiro. Using a Foucaultian approach, he views cities and the urban networks as biopolitical entities, and he highlights the interplay of large-scale security measures and micro-scale technologies of power that regulate urban (in)securities. Similar to the essay by McCann and Ward (Ch. 29), Murakami-Wood underscores the role of knowledge agents, such as the travelling technocrats, who introduce and disseminate security applications in the global network of cities.