This chapter discusses the need, methods, and benefits of building robust social connections--or social capital--across racial, cultural, economic, and geographic boundaries in neighborhoods and communities. It begins by describing the importance of building Bonding social support networks, which are often called Strong Ties. The chapter then discusses the need to also build robust Bridging and Linking social support networks or Weak Ties. It then emphasizes that both strong and weak ties are important to promote social narratives--stories--that alter unsafe, unhealthy, and unjust social norms and build the individual and collective efficacy needed to overcome today’s polarization and the many challenges communities will face during the long climate emergency. The chapter closes with examples of how community-based initiatives can build robust social support networks across boundaries.