This chapter surveys the landscape of empirical studies on cross-border trade in knowledge that use data on intellectual property rights (IPRs). Our discussion critically evaluates whether these data support the empirical findings in the studies by identifying where IPRs data are particularly useful and where these data have limitations. Additionally, we discuss the potential value of making greater use of IPRs assignment data. The goal of the chapter is to provide a reference to help policymakers evaluate the trade in knowledge literature, particularly the interpretation of IPRs-based evidence for policy decisions.