Homeowners’ activism has drawn increasing attention from China-focused scholars. There is a growing body of literature on the individual activism of nail-like households and the collective actions of homeowners in particular communities. Few researchers, however, have paid due attention to horizontal organizational building and collective action cutting across communities, the strategies homeowners have used to expand their organizational outreach and influence, and the implications of these new developments for broader state–society relations in China. This chapter aims to address this research gap. It does so by focusing on the development of the Committee of Beijing Homeowner Associations (CBHA). The CBHA is an organization that initiated the development and institutionalization of horizontal links among homeowner associations (HA) from different communities. Its organizational goals include improvement of property management-related legislation and practice, networking among and exchange between HAs, enhancing of homeowners’ self-governing capacity, and protecting the rights and interests of homeowners. To that end, the CBHA has been organizing meetings and seminars, staging collective petitions, engaging policymakers and government institutions, and assisting homeowners in their rights defense struggles in various ways. It enjoys a broad base of support, with its membership growing quickly from ten homeowners’ associations in March 2006 to 142 (accounting for 24.7 percent of the 574 homeowners’ associations in Beijing) as of July 2008. This growth has continued in subsequent years. As an illustration, in March 2017, over 300 leaders of homeowner associations participated in the Beijing Homeowners Forum—a WeChat group now serving as the main daily communication channel for HAs across Beijing. According to our data and media reports, in 2017 there were 867 HAs in Beijing, which constitutes 28.3 percent of all residential communities in the city.