There are influential studies that argue that foreign aid displaces domestic tax revenue when it is given in the form of grants. These claims are based on data that are deeply problematic: several different sources are amalgamated into one dataset, with no apparent checks on compatibility. In this article, a variety of econometric strategies are used to overcome these issues of data quality. The resulting weight of evidence points to a modest but positive effect on the part of foreign aid generally on domestic tax revenue. Fears over a negative effect for aid grants appear unwarranted, and are accounted for by the inappropriate use of data or endogeneity issues.