"This is the first paper to statistically examine the timing of interest group lobbying. It introduces a theoretical framework based on recurring structural policy windows' and argues that these types of windows should have a large effect on the intensity and timing of interest group activity. Using a new database of all lobbying expenditures in the U.S. states ranging up to 25 years, the paper shows interest group lobbying increases substantially during one of these structural windows in particular--the budgeting process. Spikes in lobbying during budgeting are driven primarily by business groups. Moreover, even groups relatively unaffected by budgets lobby more intensely during legislative budgeting, consistent with the theory that these interests are attempting to have legislators attach (de)regulatory riders to the budget bills. Overall, the paper demonstrates that these structural policy windows largely determine lobbying expenditures"--National Bureau of Economic Research web site.