Emissions trading schemes (ETS) have become popular as a policy instrument to tackle climate change. This chapter analyses the decision to deploy carbon markets and their interaction with other instruments in Mexico’s climate policy. Instrument selection has been thoroughly explored in the regulation and public policy literature (Kern et al. in Res Policy 48, 2019; Capano and Lippi in Policy Sci 50(2):269–293, 2016; Wurzel et al. in German Policy Studies 9:21–48, 2013; Harker et al. in Climate Policy 17(4):485–500, 2017; Baldwin et al. in Understanding regulation, Oxford University Press, 2012; Jordan et al. in Policy instruments in practice. Oxford handbooks online 536–549, 2011), but its application to carbon markets is mainly focused on environments such as Europe, the US and, more recently, China. The decision to adopt an ETS relies not only on specific characteristics of each instrument but also on institutional constraints and messy political considerations. A combination of preferences and institutional factors affect the choice of instruments, and the ultimate decision must be legitimate and instrumental for each context. I analyse the considerations involved in the deployment of the ETS pilot project, looking at its distinctive characteristics and those it shares with other available instruments, as well as the requirements for its implementation.