Contract is a central trope of transnational ordering. In the shadow of the various attempts to harmonize contract law at the transnational level (such as through UNIDROIT), the very institution of contract already forms the backbone of transnational interaction. Yet, as this chapter outlines, contract theory is for the most part ill-prepared to capture the constitutive role of contracts in the regulation and critique of transnational social institutions, such as global value chains or digital platforms. In such scenarios, beyond being geared toward efficiency between parties, contracts embody a plurality of rationalities and interests and form a discursive space. Albeit often in a fragile way, contracts emerge as equivalents of political institutions inasmuch as the state legal order no longer provides substantial background justice. The chapter surveys how realist and critical traditions in contract theory, in both their US and European variants, are presently being recalibrated to properly reconstruct transnational social conflicts.