* the National Council (Nationalrat) and
* the Federal Council (Bundesrat).
The National Council is composed of 183 members elected through proportional representation in a general election. This happens every five years, or earlier if the National Council prematurely moves for its own dissolution. The National Council is the dominant (albeit 'lower') house in the Austrian Parliament, and consequently the terms Parliament and National Council are commonly used synonymously.
The Federal Council is elected indirectly, through the provincial diets (Landtage) of the nine States of the Federal Republic. The states are represented in the Federal Council roughly in accordance to the size of their populations. Seats are redistributed among the states following each general census, and the overall size of the chamber is slightly variable as a result of this. The current Federal Council is composed of 62 delegates. With regard to most issues, the Federal Council only possesses a dilatory right of veto which can be overridden by the National Council. However, the Federal Council enjoys absolute veto powers over bills intended to alter the powers of either the states, or of the Federal Council itself.
The Federal Assembly (Bundesversammlung) is a body of mostly ceremonial function, consisting of the members of both houses of parliament. The Federal Assembly convenes only rarely, for instance to witness the inauguration of the Federal President. It might be noted, however, that under exceptional circumstances the Austrian constitution endows the Federal Assembly with significant responsibilities. An example of this would be its pivotal role in the hypothetic impeachment of a Federal President.
Both houses of parliament, as well as the Federal Assembly, convene in the Parliament building located on Vienna's Ringstraße.