A growing number of large-scale free trade agreements, so-called 'mega-regionals', contain both investment and labour provisions. In this chapter, we argue that this bears the potential for mainstreaming investment-labour linkage into international investment law. Prompted by this prospect, we engage in an indepth analysis of the particular components of investment-labour linkages, their potentials and shortcomings. Our main observation is that the investment-labour linkage contained in the examined agreements has the potential to contribute to a more adequate balance between investors' and workers' interests. However, since the respective provisions largely leave this linkage to the stage of treaty interpretation and implementation, the tapping of this potential will eventually depend on the willingness and ability of investors and governments.