The Senate Appropriations Committee is the largest committee in the U.S. Senate, consisting of 30 members in the 111th Congress. Its role is defined by the U.S. Constitution, which requires "appropriations made by law" prior to the expenditure of any money from the Federal treasury. The Committee, chaired by Daniel K Inouye (D-Hawaii), writes the legislation that allocates federal funds to the numerous government agencies, departments, and organizations on an annual basis. Appropriations are limited to the levels set by a Budget Resolution, drafted by the Senate Budget Committee.

12 subcommittees are tasked with drafting legislation to allocate funds to government agencies within their jurisdictions. These subcommittees are responsible for reviewing the President's budget request, hearing testimony from government officials, and drafting the spending plans for the coming fiscal year. Their work is passed on to the full Senate Appropriations Committee, which may review and modify the bills and forward them to the full Senate for consideration.

The Committee is also responsible for supplemental spending bills, which are sometimes needed in the middle of a fiscal year to compensate for emergency expenses.