While the main conservation strategy has been the establishment of government-controlled protected areas (PAs), approaches have diversified over the last decades, including devolving management rights to non-government actors, such as through conservation concessions (CCs). This review assesses the environmental and social impacts of PAs and CCs in South America. Recent studies show overall positive environmental impacts, especially reduced deforestation. Meanwhile social impacts remain less studied, but are more diverse and contested. While CCs address some social shortcomings of PAs, they exhibit their own institutional and political challenges. The review highlights a need to broaden the measures of effectiveness and pay more attention to the diverse impacts of PAs and CCs and the factors influencing them, including governance and political aspects.