This chapter dissects the US defense budget, as well as various matters in the broader field of defense economics. It provides methodologies for understanding how different defense strategies and military force postures affect that budget. The chapter also explores various ways the defense budget can be categorized, broken down, and defined. It examines issues like military readiness — how the Department of Defense ensures that its forces are ready-to-go for crises that may emerge quickly. The chapter then looks into the economics of military bases, at home and abroad. It discusses military acquisition, modernization, and innovation. The chapter then shifts to the Congressional Budget Office (CBO) figures, and analyses how they provide the backbone of the cost estimates. It highlights the core of this section — understanding the costs of US Department of Defense's (DoD) force structure by type of unit. This is probably the core of defense budgeting methodology for those seeking to understand the fiscal implications of a given defense strategy and force structure. Ultimately, the chapter investigates how two different concepts of grand strategy and/or military policy might be translated into force structure, weapons acquisition, and budget plans.