Intelligent forecasting of personnel needs is important to the public administrator in any political climate. In today's atmosphere of tax and budget cutting, however, it is vital. Budgets are under scrutiny as never before, and informal methods of estimating and justifying future personnel requirements are no longer convincing. The leaders of today's tax limitation movements are intelligent and articulate individuals with a strong following. Rising taxes, together with nearly runaway inflation, are putting an intolerable burden on many of our citizens. These citizens are beginning to demand dollar-by-dollar accountability from those who propose governmental budgets. In order to defend the legitimate needs of their agencies, public administrators must be familiar with empirical methods of personnel forecasting, methods that can be objectively defended as logical and sound, and methods that can be used with the framework of a zero based budgeting system. Among the approaches that might meet the above criteria are the population ratios method, the standards method, the needs approach, the economic determinates method, and the program specific method.' Although the focus herein is on criminal justice agencies, the methods used have application in almost any activity, and should be of interest not only to budget personnel but to the generalist administrator who have responsibility for justifying budget.