A congressional caucus is an informal group of lawmakers in the House and Senate who come together to pursue common legislative objectives. They are also referred to as coalitions, study groups, task forces, or working groups. Caucuses exist outside of, or separate and apart from, the committee system and party organizations in the House and Senate. Lawmakers form caucuses when committees and/or parties do not help them achieve their goals.

Caucuses try to shape policy outcomes directly through the legislative process or indirectly through the electoral process. They engage in a variety of activities to influence the agenda inside the House and Senate, determine the alternatives lawmakers consider during debates, and shape the final version of whatever legislation Congress eventually passes.

The largest caucuses are the party caucuses and conferences in the United States Congress, which are the partisan caucuses comprising all members of one house from one party (either the Democrats or the Republicans) in addition to any independent members who may caucus with either party. Ideological congressional caucuses can represent a political party within a political party.

Caucuses serve an informational purpose or distribute benefits to their members in some other way. They provide a way for like-minded Representatives and Senators with mutual interests and goals to get to know one another. Through these relationships, they can work together to advance their shared goals.

In summary, a congressional caucus is an informal group of lawmakers in the House and Senate who come together to pursue common legislative objectives. They try to shape policy outcomes directly or indirectly and serve an informational purpose or distribute benefits to their members in some other way.