This Article comprehensively discusses U.S. anti-treaty shopping (limitation on benefits) rules contained in U.S. income tax treaties up to and including the rules contained in the 2016 U.S. Model Treaty. In this context, anti-treaty shopping rules can be generally defined as rules intended to limit the circumstances in which residents of third countries can benefit from what was intended to be a bilateral income tax agreement between a source country and a residence country. The Article begins with an in-depth discussion of the circumstances that led to the original inclusion of anti-treaty shopping limitations in U.S. income tax treaties, describes the rationales for adopting these rules, places the limitation on benefits rules in the context of certain other contemporaneous U.S. tax law changes, discusses where the Treasury Department drafters looked for inspiration in developing the U.S. anti-treaty shopping rules, and summarizes the initial limited anti-treaty shopping rules inserted into U.S. income tax treaties during the 1970s and 1980s. The Article then discusses the limitation on benefits tests applicable to different categories of taxpayers: individuals, governments and governmental entities, public companies, subsidiaries of public companies, companies covered by the stock ownership-base erosion test, headquarter companies, and not-for-profit entities. It also describes the so-called “principal purpose” test which remains applicable in a limited number of U.S. income tax treaties. A taxpayer satisfying one of these tests is typically entitled to all treaty benefits (assuming compliance with other treaty requirements). The Article then explores the active trade or business test, the derivative benefits test, and the shipping/aircraft test, which grant treaty benefits to a taxpayer on a more limited, item-of-income by item-of-income, basis. In the case of each set of rules, the Article details their development over time as well as their technical issues and limitations. The Article also describes additional limitations frequently imposed by U.S. limitation on benefits articles such as the triangular case limitation rules. It also provides a discussion of the “safety valve” test (whose purpose is to permit treaty benefits in cases where a taxpayer did not satisfy one of the other limitation on benefits tests but whose scope has been narrowly construed by the U.S. tax authorities) as well as ongoing litigation under the test. The Article’s conclusion discusses whether (and the degree to which) the limitation on benefits rules have actually accomplished their purpose (or purposes) and suggests that Treasury’s rationale for these rules has continuously evolved in ways well beyond the purpose of limiting third country use of U.S. income tax treaties. The Article suggests that the U.S. limitation on benefits rules can be wildly over-inclusive and wildly under-inclusive, remain technically problematic even after nearly 50 years of development, and, because of their ever-increasing complexity, are unlikely to be accepted by most other countries as an international model for limiting treaty abuse. Indeed, because of their technical issues and problems, it is not unreasonable to expect that the most recent version of these rules will make it more difficult than ever for the United States in the future to negotiate revised or new income tax treaties.