Decisions about "who gets what, when, and how" are perhaps the most important that any government must make. So it should not be remarkable that around the world, public officials responsible for public budgeting are facing demands--from their own citizenry, other government officials, economic actors, and increasingly from international sources--to make their patterns of spending more transparent and their processes more participatory.

Surprisingly, rigorous analysis of the causes and consequences of fiscal transparency is thin at best. Open Budgets seeks to fill this gap in...