The use of committees as crucial centres of policymaking, oversight of federal agencies, and public education is an organising principle of the contemporary Congress. Committees are presumed to be the primary locus through which the work of Congress is organised, and where public policy proposals first receive substantive consideration. By using committees, the Senate enables itself to manage a large volume of legislative, investigative and oversight activity, and support the representational duties of Senators. The focus of the workload and activity indicators presented in this book is action on legislative measures referred to committees. These indicators illuminate certain kinds of congressional workload and activity.