Implementation of carbon emissions trading schemes such as the European Union’s Emissions Trading Scheme requires consideration of how to properly characterize the newly-created emissions credits under various domestic and international law frameworks. Notably absent from the literature on emissions trading is an analysis of whether emissions credits can be characterized as investments, thereby implicating international investment law protections against expropriation and discrimination and giving rise to guarantees of fair and equitable treatment. This Note analyzes the International Centre for Settlement of Investment Disputes’s objective definition of “investment” as well as treaty-specific definitions of “investment” and concludes that carbon credits are properly considered investments. Next, the Note considers the types of investor claims that could be brought against host states if carbon credits are treated as investments. Because of the potential costs to host states in defending against such claims, states’ willingness to adopt carbon trading schemes may be chilled. This risk of regulatory chill, coupled with the global importance of national measures to combat climate change, counsels in favor of limiting the scope of rights afforded to investors. This Note therefore concludes by setting out a range of proposals for enacting such limits.