The term social capital has been used to describe the networks and other forces that build social cohesion, personal investment, reciprocity, civic engagement, and interpersonal trust among residents in a community. With the exception of three Australian reports describing positive associations between companion animal ownership and social capital, the literature has neglected to include the presence or absence of companion animal residents of communities as factors that could potentially affect social capital and serve as protective factors for community well-being. Companion animals are present in significantly large numbers in most communities, where they have considerable economic impact and provide emotional and physiologic health benefits and social support to their owners. Companion animals may mitigate the stresses of urban living and counteract what has been called "nature-deficit disorder." Conversely, they may also be the victims of cruelty, abuse and neglect which can adversely affect the quality of life and social capital of a community. Efforts to measure the impact of companion animals on social capital are constrained by a lack of accurate data on companion animal populations and by gaps in our knowledge of attitudes toward companion animal ownership, particularly in communities of color. An agenda for research, public policy and programmatic activities to address these gaps is proposed to help determine whether the resilience and protective factors which companion animals can offer individuals extend to community populations as well.