Do education choice programs take money from public school districts, leaving fewer resources for students who remain? The issue at the heart of this question is one of the most powerful arguments offered by skeptics and opponents of such programs. A district's total budget might expand or contract as its student population expands or contracts. If enrollment contracts, it could be that students moved to a different town or left via a private school choice program, or for other reasons. The important question is what resources will be available for students who remain. This question will become more pressing as, according to federal estimates, public school enrollments nationally are projected to fall by more than 2.7 million students between fall 2022 and fall 2031--a decline of 5.5% This report analyzes what happens when districts' enrollments change, either up or down. What do these changes do to their finances, or to the resources available to serve students? Data from the years immediately preceding the COVID-19 pandemic offer some ideas. This report provides the first direct evidence of how enrollment declines affect the resources available for students who remain. The report analyses the fiscal effects of enrollment drops over a one-year period (academic year 201819), a four-year period (AY 1995-1999), and a 21-year period (AY 1998-2019). The three different periods let us look at the short-term, medium-term, and long-term effects of enrollment shifts.