The National Assembly of the Philippines (Tagalog: Kapulungáng Pambansâ ng Pilipinas, Spanish: Asamblea Nacional de Filipinas) refers to the legislature of the Commonwealth of the Philippines from 1935 to 1941, and of the Second Philippine Republic during the Japanese occupation. The National Assembly of the Commonwealth was created under the 1935 Constitution, which served as the Philippines' fundamental law to prepare it for its independence from the United States of America.

The National Assembly during the Japanese occupation of the Philippines during the Second World War in the Pacific was created by the 1943 Constitution. With the invasion of the Philippines, the Commonwealth government had gone into exile to the United States. It left behind a skeletal bureaucracy whose officials formed a government under the Japanese Imperial Army. In an attempt to win the loyalty of Filipinos, the Japanese established a nominally independent Republic of the Philippines, with a National Assembly as its legislative body. The Second Philippine Republic was only recognized by the Axis powers.

Prior to 1935, the Philippine Islands, an insular area of the United States had the bicameral Philippine Legislature as its legislative body. The Philippine Legislature was established in 1907 and reorganized in 1916, pursuant to a U.S. federal law known as the Jones Law. The Jones Law provided for a Senate and a House of Representatives, whose membership were elected except for a few, which were appointed by the U.S. Governor-General without the need for confirmation. The Governor-General, being the chief executive of the territory, also exercised the power to veto any of the Philippine Legislature's legislations.

In 1934, Filipino politicians obtained the passage of a Philippine independence law known as the Tydings–McDuffie Act. It was crafted to prepare the Philippines for its eventual independence after a ten-year period. The Tydings–McDuffie Act also enabled them to draft and adopt a constitution, subject to the concurrence of the U.S. president.

In the constitutional convention that followed, a unicameral National Assembly was adopted. This came after the failure of the constitutional convention delegates to agree on the setup of the bicameral system that was favored by the majority. It also set the ceiling on its membership to a maximum of 120, that were to be elected every three years; similar to what the Jones Law had provided. It entitled every province, regardless of its population to have at least one representative. The convention likewise provided for the direct election of representatives from the non-predominantly Christian areas previously appointed by the U.S. Governor-General.

After the 1935 Constitution was ratified, elections were held on September 17, 1935, for the 98 members of the National Assembly; simultaneous with the elections for the Commonwealth President and Vice President. The Philippine Commonwealth was inaugurated on November 15, 1935, and thus the term of the elected officials began. The National Assembly first met officially on November 25, ten days after the Commonwealth government was inaugurated and elected Gil M. Montilla of Negros Occidental as its Speaker. It soon organized itself into three commissions and 40 standing committees, when it adopted its rules on December 6.

The assembly had the task of passing laws to prepare the Philippines for its eventual independence. Certain laws dealing with foreign relations and finance however, still required the approval of the U.S. president. Commonwealth President Manuel L. Quezon, who had practical control of the National Assembly, addressed the body on its inaugural session and laid-out his administration's priorities and legislative agenda. He was able to secure the passage of important legislation without much opposition, after he diluted the powers of the Speaker to a mere presiding officer. Among the first of such measures were the National Defense Act of 1935, which created the Philippine Army; the creation of the National Economic Council, to serve as an advisory body on economic matters; and the creation of the Court of Appeals. Several economic measures were also tackled, including the impending difficulties on the phase out of free trade between the Philippines and the United States after independence, setting a minimum wage, and the imposition of new taxes among others.

Most of the bills enacted were drafted by the executive branch and the few that originated from the members themselves were often vetoed by Quezon. In the sessions of the First National Assembly in 1936, 236 bills were passed, of which 25 bills were vetoed; while on its 1938 session, 44 out of 105 bills were vetoed due to practical defects, including one which proposed to make religious instruction compulsory in schools – clearly violating the constitutional provision on the separation of Church and State. The sporadic vetoing of its legislation prompted the "rubber stamp" legislature to criticize Quezon's policies. It then began to assert its independence from the executive. In line with this, the National Assembly went on to reinstate the inherent powers of the Speaker.