Introduction Civic engagement, whether in environmentalism or any other domain of the public sphere, is a collective action of public consciousness and social influence. However, this kind of collective action has been largely lacking in China. Deeply rooted in a tradition of relational particularism (Walder 1986), Chinese individuals are normatively expected to orient their interests and values toward the family, kinship, or similar primary groups, rather than the public sphere of the commonwealth in larger society. To a large extent, public consciousness is nonexistent or extremely weak when matters of interest are beyond the worlds of intimacy, but social influence is most effective within the confines of relationally defined network circles (Gold et al. 2002). In this chapter I develop a theoretical model to explain the extent to which network social capital increases environmental engagement in the Chinese context. Network social capital refers to information-and influence-relevant resources of a social network. As can be expected, individuals who live in a larger, less dense, and resource-richer networks are oriented toward a much larger world of social relevance than their counterparts who live in a smaller, denser, and resource-poorer network. Compared with the latter, the former individuals are expected to have greater environmental consciousness, and are therefore more likely to participate in environmental programs organized locally or around the nation. I begin with a review of China’s record on civic engagement and environmentalism, exploring how China’s environmental problems have been generated by the changing developmental strategies of a Communist party-state for the past six decades. Next, I review sociological literature on the cultural and social meanings of network social capital in China; my focus is on how guanxi (interpersonal connections of favor exchange) is related to the notion of network social capital. This is followed by an elaboration of a theoretical model that relates network social capital to environmental engagement. Research hypotheses that are derived from this model are tested with the assistance of a 2003 Chinese General Social Survey (hereafter CGSS), a nationally representative household survey. In the conclusion I draw a few broader implications of the findings for research on social capital and civic engagement beyond the topic of environmentalism.