This chapter reviews what might be termed the classic or traditional budgetary theories that dominated discussion in the realm from the immediate post-World War II era to the 1990s. It explores the various strains of thought associated with what might be termed the Performance Measurement Revolution and related topics such as benchmarking and re-engineering. The sheer volume of writing in the performance measurement arena suggests that a new era in the arena of public budgeting has arrived. Budgeting may be too complex for any one set of theoretical propositions to explain. But an era of cutback management and enhanced interest in government performance suggest that as a new millennium begins, the search for tools that enhance the rationality of government expenditures-or justification for reducing government-will keep the search for a budget theory alive and well. Training in performance measurement and budgeting is becoming a staple of Master of Public Administration curriculums.