A constituent assembly (sometimes also known as a constitutional convention or constitutional assembly) is a body composed for the purpose of drafting or adopting a constitution. As the fundamental document constituting a state, a constitution cannot normally be modified or amended by the state's normal legislative procedures; instead a constituent assembly, the rules for which are normally laid down in the constitution, must be set up. A constituent assembly is usually set up for its specific purpose, which it carries out in a relatively short time, after which the assembly is dissolved.

Unlike forms of constitution-making in which a constitution is unilaterally imposed by a sovereign lawmaker, the constituent assembly creates a constitution through “internally imposed” actions, in that members of the constituent assembly are themselves citizens, but not necessarily the rulers, of the country for which they are creating a constitution. As described by Columbia University Social Sciences Professor Jon Elster:

The Constitution of India (Hindi: भारतीय संविधान; see also names in the other official languages) is the supreme law of India. It lays down the framework defining fundamental political principles, establishes the structure, procedures, powers, and duties of government institutions, and sets out fundamental rights, directive principles, and the duties of citizens. It is the longest written constitution of any sovereign country in the world, containing 444 articles in 24 parts, 12 schedules and 97 amendments. Besides the English version, there is an official Hindi translation. Bodhisattva Dr. Babasaheb Ambedkar[bhimrao ramji Ambedkar] is Chief Architect of Indian Constitution.

The Constitution was enacted by the Constituent Assembly on 26 November 1949, and came into effect on 26 January 1950. The date 26 January was chosen to commemorate the Purna Swaraj declaration of independence of 1930. With its adoption, the Union of India officially became the modern and contemporary Republic of India and it replaced the Government of India Act 1935 as the country's fundamental governing document. The Constitution declares India to be a sovereign, socialist, secular, democratic republic, assuring its citizens of justice, equality, and liberty, and endeavours to promote fraternity among them. The words "socialist" and "secular" were added to the definition in 1976 by constitutional amendment. India celebrates the adoption of the constitution on 26 January each year as Republic Day.