“Payments for ecosystem services” (PES) represents a new form of environmental governance rooted in the logics of capitalist economics. As such, PES frequently produces new conceptions and material forms of nature that embody the principles of neoliberal ideology. This thesis explores the processes by which these policies have been deployed and taken root in Costa Rica, one of the foremost sites of financialized conservation worldwide. It provides a historical account of policy formation and the neoliberalization of Costa Rican nature. I situate this analysis in a critique of capitalist logic, explaining the particular type of neoliberalization that emerges as a consequence of capital's own internal contradictions. I place particular emphasis on ideological inconsistencies in the deployment of neoliberal ideals while highlighting the justice implications that inevitably still emerge. I do so by adopting a critical political-ecology perspective that sees questions of environmental management as fundamental questions of social and environmental justice – how are conservation mechanisms designed, by whom, for what purposes, and to whose ultimate benefit? Specifically, I consider three aspects of neoliberalization in Costa Rica's national Pagos por Servicios Ambientales (PSA) program: the design of a new market-like financing mechanism; the promotion of individualized contracting and participation; and the expansion of exclusionary land management practices. I show that these actions produce the conditions for uneven development, facilitate the consolidation of control over resources, and enable the accumulation of benefits among larger, wealthier landowners. I further explore conceptual understandings of neoliberalism (as ideology or process) and address the growing concern in the critical literature with ways that policy deviates from doctrine. I explain that such an emphasis on ideologically divergent practice distracts from the material and justice effects of encroaching neoliberalization, which invariably operates in partial and unfinished ways. Finally, I revisit the role of the internal contradictions of capital in producing the patterns of governance that constitute this era of neoliberal environmentalism.