This paper demonstrates how implicit cultural evolution theory (CE) is used in adaptive management of grassroots campaigns of resistance against environmentally destructive industry and government to facilitate sustainable outcomes. For an action to be sustainable, it must be stable against political pressures. By bringing attention to the effects of social transmission—recruitment to a cause, learning across campaigns, and the transmission or cultivation of solidarity sentiments—cultural evolution presents a framework for tracking social dynamics essential for the sustainability of resistance projects. This is illustrated with examples from direct action grassroots activism in First Nations communities in northern British Columbia, Canada in the context of fights against unsustainable industrial projects. Specifically, grassroots activists work with an implicit CE theory of social transmission of values that posits that expansive, large-group organizing can get large numbers moderately committed to cause but that organizing focusing on small groups is more successful at transmitting intense commitment and adherence to First Nations norms. In the case of direct action resistance, such intense commitment is more vital than numbers for success. Further, grassroots activists have self-consciously developed institutions for the rapid transmission of policy innovations, accelerating the constructive evolution of tactics.