With World Trade Organization negotiations stagnant, and preferential trade agreements (PTAs) rapidly proliferating, international trade relations are shifting markedly toward bilateralism. The resulting fragmentation in the international trade regime poses serious risks to economic welfare and the coherence of international trade law. Similar challenges have been faced in the international investment regime, which is comprised of a highly fragmented network of bilateral investment treaties (BITs). However, scholars have identified several mechanisms that promote harmonization in the international investment regime. Among these are cross-treaty interpretation in dispute settlement and the inclusion of most-favoured nation (MFN) clauses in BITs. This paper assesses the scope for these two mechanisms to emerge in the international trade regime by comparing the legal framework, institutional dynamics, and political economy of the trade and investment regimes. The analysis suggests that cross-treaty interpretation is likely to emerge in the trade regime as PTA dispute settlement activity increases and that greater use of MFN clauses in PTAs is a viable possibility. These developments would mitigate the effects of fragmentation and advance harmonization in the international trade regime.