This chapter assesses the intersection between climate change and two of the most significant preferential trade agreements (PTAs) ever to be contemplated—the Trans-Pacific Partnership Agreement (TPP) and the Trans-Atlantic Trade and Investment Partnership (TTIP). These agreements would, upon entry into force, cover close to one-third and one-quarter of world trade flows respectively. This chapter begins by addressing the competing rationales for covering or omitting climate change in PTAs such as the TPP and TTIP. It then reviews the varied and evolving approaches of the EU, US, and other key negotiating parties to referencing and addressing climate change in their past PTAs. At one end of the spectrum, some are silent on climate change and environmental matters altogether. At the other end, some include binding obligations to implement international climate treaties. This chapter then proceeds to evaluate how general, non-specific environmental obligations in PTAs, such as the TPP and TTIP apply to domestic climate law, such as through binding existing levels of domestic climate ambition. It then surveys the prospect for liberalization of market access for environmental goods and services under the TPP and TTIP, and how this could assist climate mitigation and adaptation objectives. The chapter concludes by analysing the emergence of climate change in a series of recent trade and investment disputes, and the extent to which similar climate-related disputes could arise within the TPP and TTIP.