Greening the Greyfields uses ‘greening’ as a term related to the regeneration of an urban area, as well as to the choice of environmentally beneficial (or at least neutral) technology for new urban development. This chapter will outline how new twenty-first-century green urban infrastructures can help realise the value proposition of regenerating established middle suburbs. The technologies covered include energy, water, and waste systems, along with smart information and communications technology (ICT) systems that are needed to make the ‘distributed green technology’ work efficiently and equitably. Micro-mobility (scooters and bikes) is likely to help accessibility at a precinct scale and will be discussed in the next chapter, although they certainly fit within the new distributed infrastructure model. While this chapter looks at ‘greening’ in terms of ‘green tech’, Chapter 5 will look at nature-based solutions more broadly. Greening the greyfields provides the opportunity for new ‘green tech’ to be introduced in urban development in an integrated way.