This paper describes a new approach to examining public budgeting problems called the demographic budget. The demographic budget is a model that uses the size and characteristics of the population to forecast long-range government purchases of goods and services. Underlying this method is the assumption that the size of the population that has traditionally consumed a government service will drive the purchases for that service. Currently, economic models are widely used to forecast long-range government spending, using monetary variables to simulate the complex inter-relationships of the economy. The demographic model uses the size of an age group and the rate at which that age group consumes a government service to explain and then predict purchases for that service. Since the demographic model is easier to understand than an economic model, forecasts from it are more likely to be used by policymakers, and they may also be more accurate than forecasts from economic models.