The Frankfurt Parliament (German: Frankfurter Nationalversammlung, literally Frankfurt National Assembly) was the first freely elected parliament for all of Germany, including the German-populated areas of Austria-Hungary, elected on 1 May 1848 (see German federal election, 1848).The session was held from 18 May 1848 to 31 May 1849, in the Paulskirche at Frankfurt am Main. Its existence was both part of and the result of the "March Revolution" within the states of the German Confederation.

After long and controversial debates, the assembly produced the so-called Frankfurt Constitution (Paulskirchenverfassung or St. Paul's Church Constitution, actually Verfassung des Deutschen Reiches) which proclaimed a German Empire based on the principles of parliamentary democracy. This constitution fulfilled the main demands of the liberal and nationalist movements of the Vormrz and provided a foundation of basic rights, both of which stood in opposition to Metternich's system of Restoration. The parliament also proposed a constitutional monarchy headed by a hereditary emperor (Kaiser).

The Prussian king Frederick William IV refused to accept the office of emperor when it was offered to him on the grounds that such a constitution and such an offer were an abridgment of the rights of the princes of the individual German states. In the 20th century, however, major elements of the Frankfurt constitution became models for the Weimar Constitution of 1919 and the Basic Law for the Federal Republic of Germany of 1949.

In politics, a national assembly is either a unicameral legislature, the lower house of a bicameral legislature, or both houses of a bicameral legislature together. In the English language it generally means "an assembly composed of the representatives of the nation." The population base represented by this name is manifestly the nation as a whole, as opposed to a geographically select population, such as that represented by a provincial assembly. The powers of a National Assembly vary according to the type of government. It may possess all the powers of government, generally governing by committee, or it may function solely within the legislative branch of the government.

The name also must be distinguished from the concept. Conceptually such an institution may appear under variety of names, especially if "national assembly" is being used to translate foreign names of the same concept into English. Also, the degree to which the National Assembly speaks for the nation is a variable. To achieve a quorum, the ancient Athenian Assembly employed Scythian police to arrest citizens at random from the street. On the other hand, the early Parliaments of Europe were mainly of an aristocratic composition. The word had its origins and inspirations from the National Assembly that was responsible for drafting a constitution during the French Revolution.

The exact words, "national assembly," have been used prolifically in the international community of nations since the 18th and 19th centuries, considered the Age of Revolution in western Europe. Nations that formed republics in this age subsequently formed empires. Extensive cross-cultural influences brought much of their language and institutions to the provinces. When these empires collapsed finally, the emancipated countries formed states and other institutions on the model of the former imperial nations. Some examples of international influences are as follows:

In Germany, a Nationalversammlung was elected following the revolutions of 1848–1849 and 1918–1919, to be replaced by a permanent parliament (Reichstag) later. The legislature of the Estado Novo regime in Portugal was known as the National Assembly. The national assembly was also defined in the Republic of China constitution. This is different from the Legislative Yuan by the ROC constitution. In 2005, Taiwan revised the constitution and the national assembly was abolished. Examples have multiplied greatly under the policy of self-determination adopted by the western nations. Many more are to be found in the articles listed below.