This report analyzes contracting for products, services, and research & development (R&D) by the Department of Defense (Do D) and its key components. In provides an in-depth look at trends in Do D contracting since 2000, and provides an initial picture of the impact that sequestration has had on Do D contracting and the supporting industrial base. This fourth edition of the Do D report updates reports from previous years and provides greater breadth of analysis. The report examines trends in Do D contracting, breaking down Do D contract spending by a variety of contract and vendor characteristics. The report then uses this data to address key policy questions related to Do D contracting.