In light of the evident disparity between the movement toward sustainable development provisions in international investment agreements (IIAs) and the barriers potentially posed to the enforcement of environmental safeguards by the exercise of investor-state dispute settlement (ISDS) rights, this chapter explores the complex relationship between regional investment treaties (RITs), bilateral investment treaties (BITs), IIAs and natural resource protection. After briefly considering some substantive provisions in select IIAs which directly address natural resource issues, it explores how IIAs – including their standard protection mechanisms and ISDS processes – can promote, and in some cases, hinder the ability for host states to achieve natural resource protection. The chapter considers options available to developing countries to improve natural resource protect ion through the incorporation of amicus curiae submissions into ISDS processes and the use of sustainability impact assessments (SIAs) in IIA negotiations. Significant reform is underway to improve IIA governance and align IIAs with best practices.