A long line of research, beginning with Macaulay's (1963) well‐known study of “Non‐Contractual Relations in Business,” suggests that the formal trappings of domestic law often have effects on private behavior that are, at best, “indirect, subtle, and ambiguous” (Macaulay 1984:155). Law and society scholars have spent somewhat less time exploring whether international law's effects on behavior are similarly attenuated. In this article I examine whether foreign investors take the presence of strong formal international legal protections into account when deciding where to invest. I focus on whether the presence of bilateral investment treaties, or BITs, meaningfully influences investment decisions. I present results from a statistical analysis that examines whether the formally strongest BITs—those that guarantee investors access to international arbitration to enforce investors' international legal rights—are associated with greater investment flows. I find no clear link between treaty protections and investment, a finding consistent with past law and society research but in tension with claims common in the BIT literature that the treaties should have dramatic effects on investor behavior.