The ringing of bells throughout the Capitol and the three Senate Office Buildings signals the opening of a day's session, and announces votes, quorum calls, and other legislative activities. The bells correspond with a series of lights above the doors on the north side of the chamber.

At the beginning of each daily meeting, the presiding officer accompanies the Senate chaplain to the rostrum for an opening prayer. The Vice President of the United States serves as President of the Senate and therefore its presiding officer. In the Vice President's absence, the President pro tempore — generally, but not always, the most senior member of the majority party — presides, or will designate other senators from the majority party to take the chair. Senators must direct all remarks to the presiding officer, whom they address as "Mr. President," or "Madam President."

At the long marble desk in front of the presiding officer are the clerks of the Senate. The journal clerk records minutes of the proceedings, as is required by the Constitution. The parliamentarian advises the presiding officer and members regarding Senate rules and procedures. The legislative clerk calls the roll and receives bills, resolutions, and amendments offered by members. At the two mahogany desks before these clerks are the staffs of the party secretaries and the Democratic Policy Committee and the Republican Scheduling Office, who keep members of their parties informed as to the subject matter at hand, and tally the votes cast. Senate pages are stationed on both sides of the rostrum. They serve as messengers for senators and are selected from among students who are in their junior year of high school. The pages attend early morning classes in a school located at the Library of Congress.

The Majority and Minority Leaders occupy the front desks on their respective sides of the center aisle, with the Republicans to the presiding officer's left and the Democrats to the right. The more senior members of each party have priority in seat selection and generally sit toward the front and center of the chamber. As a senator speaks, an official reporter of debates stands nearby, taking a verbatim account of everything said.

Reporters work 10-minute shifts in the chamber and then immediately transcribe their notes. By the next morning, the entire day's proceedings, along with related materials, will be printed in the Congressional Record.

In 1986 the Senate began live radio and television coverage of its floor proceedings. The Senate's gavel-to-gavel proceedings are beamed by the nonprofit Cable Satellite Public Affairs Network (C-SPAN) to a satellite orbiting high above the equator. These signals are returned to cable television systems across the continent for distribution to viewers. Videotapes of Senate sessions are available to the public at the National Archives and the Library of Congress.

The Senate usually begins the day with 10-minute speeches by the Majority and Minority Leaders, followed by a period designated as "Morning Business." Members introduce bills and resolutions, which are referred to the various committees for consideration. Members may also request permission to speak briefly on any subject that concerns them. Following "Morning Business" the Senate may consider either executive or legislative business. During an executive session the Senate may consider any nomination and treaty that the president submits for the Senate's advice and consent. Nominations are confirmed by a simple majority, but the Constitution requires a two-thirds vote of the Senate to approve treaties. For much of the Senate's history, all executive sessions were conducted in secret, with the galleries cleared and the doors locked, enabling senators to speak freely about the character of nominees and to avoid causing any embarrassment to the nation's treaty partners. Not until 1929 were executive sessions routinely opened to the public and the press.

Legislative business consumes the largest share of the Senate's time. When committees report out legislation, the Majority Leader will attempt to schedule it for debate in the chamber. If both parties have agreed to the bill, it may be enacted simply by "unanimous consent," with only a brief reading of its title and a request by the leadership that it be adopted without objection, generally by voice vote. If a single member objects, however, the Senate might not consider the bill at all, or may debate it at length; a roll call vote might be ordered.

The Senate has long operated under the principle of "unlimited debate"; that is, all members may speak for as long as they wish on the matter under consideration. To expedite matters, the leadership may request unanimous consent to establish a time limit on debate for a specific legislative measure. Extended debate designed to defeat or amend a bill by dilatory tactics is called a "filibuster." Those senators opposed to a filibuster may file a "cloture" motion, signed by at least sixteen senators, under which a vote of sixty senators can limit the remaining debate.

When a bill is being debated, the floor managers of the two parties will often take the front row, center aisle seats of the Majority and Minority Leaders. If a time limit has been established, they will allot portions of their times to senators wishing to speak for or against the bill. It is not unusual to find only a few members in the chamber at any given time during the debate, with other senators attending committee hearings or at work in their offices. Members'offices are equipped with "hot lines" and televisions that provide instant access to what is happening on the Senate floor. When the bells signal a vote, all members present enter the chamber and record their "ayes" and "noes."

Whenever the Senate is in session, the American flag flies above the chamber's roof. When the legislative load is especially heavy, or when a filibuster is under way, the Senate may hold sessions long into the night or around the clock. A lantern at the top of the Capitol dome is always lit during these night sessions. Whether at two in the morning or two in the afternoon, the public is always welcome to the galleries to witness the proceedings.