How can social innovation initiatives in cities be scaled to provide systemic and enduring impact on reducing GHG emissions? Academic and practitioners’ literature offers a number of conceptualizations of social innovation scaling strategies, including the popular “scaling up, out and deep” framework. In this chapter, scaling methods are presented to support cities to amplify social innovation impact. Based on cities’ social innovation readiness level, social innovation pathways can range from preparatory phases—including capacity building and mobilizing funds—to mapping the ecosystem, and to systematically embedding social innovation for climate neutrality in all cities’ activities, including communication strategies, public procurement, circular economy, urban planning, and policy co-creation.