The National State Assembly (NSA) was the legislative body of Sri Lanka established in May 1972 under the First Republican Constitution.

The assembly was introduced by Prime Minister Sirimavo Bandaranaike under the United Front Government replacing the Parliament of Ceylon, a bicameral arrangement set up with the Soulbury Commission.

It gave the government the power to act without constitutional restraints, with the courts having no rights to question the validity of the laws passed by the assembly.

The assembly saw the introduction of socialist principles and a constitutional foundation to the pre-eminent position of Sinhala and Buddhism.

[2] The assembly was unicameral and initially consisted of the 151 elected members of its predecessor the House of Representatives, as the Senate had been abolished in 1971.