Evidence is growing that transition dynamics in urban contexts cannot be understood based solely on the specific actors and dynamics inside a city, but that they span actors and processes at multiple interrelated spatial scales. This chapter addresses this research gap by elaborating on the ability of urban actors to mediate local and global resource flows as a precondition for niche formation. It draws on recent insights from economic geography and technological innovation system studies and argues that an important element in explaining early niche formation processes is urban actors' ability to combine territorially embedded innovation processes with mobilizing resources through networks reaching outside the city. The chapter proposes the concept of socio-spatial anchoring to analyze how local niche activities become connected to international technological innovation systems and analyze which key roles urban actors fulfill in these multi-scalar innovation systems. It illustrates analytical framework with the transition to on-site water recycling (OST) technology in China.