On one level, Program Earth covers a wide range of topics, from forests and webcams to migration and climate change, garbage patches in oceans and air pollution in urban areas, smart cities and digital participation, as well as urban development. A prospective reader could approach any one of these sections and find a unique trajectory through the material. For instance, an urbanist could focus only on the “Urban Sensing” section, while someone engaged with environmental science could focus on the “Wild Sensing” and “Pollution Sensing” sections.On another level, the introduction does set out some of the thinking and practicing with sensors and environmental monitoring that I have been engaged with since the early 2000s. Ideally, a reader would encounter this section first to be able to scan the environmental sensing technologies included in the book, as well as to consider the particular way in which environments and environmental processes are foregrounded when working through the operations of sensor technologies.With that said, often one of the first ways I encounter new books of interest is to skip quickly from the introduction to the bibliography. If prospective readers were to do the same with Program Earth, they might find a rather wide assortment of literatures, from philosophy and science and technology studies, to computational studies, environmental science texts and more. This study is necessarily transdisciplinary, but at the same time attempts to consolidate work around the core topic of environmental sensing technologies from a perspective that attempts to open up the often tech-centric approaches to these devices to consider their wider implications for our socio-political and cultural ways of life.Program Earth is very much written as a companion text to the ongoing practice-based research that I am developing through the collaborative project, Citizen Sense. The Citizen Sense project investigates the use of low-cost environmental monitoring technologies that are increasingly pervasive and that carry the promise of making users of these technologies more equipped and capable environmental citizens.It goes without saying that we are at a critical moment when it comes to attending to and tuning in to environments under stress. However, from climate change to air pollution, many of the promoted “solutions” to environmental problems are often presented as depoliticized technological approaches by which we are meant to be able to engineer our way out of our collective dilemmas.Program Earth attempts to rethink how these problems are cast, not to eliminate sensor technologies, but instead to make the case that different and more open and indeterminate engagements with these technologies could generate different political possibilities.In this way, the book engages with the wider set of developments related to environmental sensing so that a more informed approach might be developed in relation to sensing technologies. Yet it does not offer a prescriptive solution for how to proceed with the increasing spread of sensor technologies. Instead, it offers a set of critical, creative and experimental resources for asking why these technologies have gained a foothold in the way that they have. And it suggests that we might encounter these technologies differently so that other environments and environmental relations—along with political subjects—could be formed.While the text is written as a theoretical and empirical account, it is very much aligned with sensor technology practices that I am collaboratively undertaking. In this way, I hope that Program Earth might then generate related theoretical and practical inquires, that at once offer us strategies for analyzing and rethinking technologies, while also reworking and adopting them in more generative and generous arrangements.