This is a draft chapter for Sage Handbook of International Relations, 2nd Edition, which offers a critical assessment of bridge building and pluralism in contemporary international-relations (IR) theory. I begin by placing recent moves towards theoretical synthesis in context, asking why one saw an upsurge of interest in bridge-building only beginning in the mid-1990s. Then I assess these efforts in three areas – international institutions, normative theory, and studies of civil war – in each case, detailing how and to what extent theoretical pluralism has come to define a particular subfield. I argue that contemporary IR does look different, and better, thanks to synthesis and bridge building. In conclusion I note two challenges – theoretical cumulation and meta-theory. These, I argue, should be at the heart of a reinvigorated research program on synthesis, one where theory is taken seriously and epistemological divides are transgressed
