Nearly four decades ago, in a path-breaking book, Aaron Wildavsky taught us, among other things, that “in the most integral sense the budget lies at the heart of the political process” (The Politics of the Budgetary Process, 1964, p. 5). Building on Wildavsky's study, many scholars have contributed to our understanding of various aspects of budget policy and politics. Some have discussed the role of trust funds in the federal budget, but none have made them the central focus of their research. Eric Patashnick fills an important void in the literature by explaining why trust funds are created and how they affect deliberation over tax and spending decisions. Using the trust fund mechanism as a point of reference, Patashnik also tests theories of policy history, public choice, and institutionalism.