This article develops a conceptual framework to theorize the processes of mutual penetration between civil society, the state, and the economy, where incumbents and challengers continuously formulate new strategies against each other. We criticize the prevailing Weberian and Tocquevillian concepts of civil society, and then, drawing on research in social movements and comparative political economy, propose a new framework: the politics of forward and backward infiltration. Under each form of infiltration, we delineate three submodes: the politics of influence, the politics of substitution, and the politics of occupation, which correspond to strategies for discursive influence, functional replacement, and institutional takeover, respectively. We challenge the exclusive focus on the politics of influence as inadequate for analyzing these processes, while highlighting the other two modes as necessary additions. Finally, we elucidate the implications of our theory of forward and backward infiltration for the study of civil society and participatory democracy more generally.