The Constitution of India was enacted by the Constituent Assembly set up under the Cabinet Mission Plan, 1946.

The Cabinet Mission Plan was a proposal put forth by the British government in 1946 to discuss and determine the future of India. It aimed to resolve the political deadlock between the Indian National Congress and the Muslim League regarding self-governance and the partition of India.

Constituent Assembly:
- The Constituent Assembly was a body of representatives elected by the Provincial Legislative Assemblies in British India.
- Its primary task was to draft and enact a new constitution for India that would serve as the foundation of the country's governance after independence.

Formation of the Constituent Assembly:
- The Constituent Assembly was formed based on the provisions of the Cabinet Mission Plan.
- The plan proposed the creation of a Constituent Assembly consisting of representatives from all major political parties, including the Indian National Congress and the Muslim League.
- The Assembly would be responsible for drafting the constitution and determining the future political structure of India.

Composition and Functions:
- The Constituent Assembly consisted of 389 members, including representatives from the princely states and minorities.
- Dr. Rajendra Prasad was elected as the President of the Assembly, and B.R. Ambedkar was appointed as the Chairman of the Drafting Committee.
- The Assembly held its first meeting on December 9, 1946, and continued its work for almost three years.
- It debated and discussed various provisions, principles, and articles to be included in the constitution.
- The Assembly also took into account the reports and recommendations of various committees and expert groups.

Enactment of the Constitution:
- After months of deliberation and extensive discussions, the Constituent Assembly adopted the final draft of the Constitution on November 26, 1949.
- The Constitution of India came into effect on January 26, 1950, marking the birth of the Republic of India.
- The Constitution provided a framework for the governance of the country, including fundamental rights, the structure of government, and the division of powers between the center and the states.

Conclusion:
- The Constitution of India was enacted by the Constituent Assembly set up under the Cabinet Mission Plan, 1946.
- The Constituent Assembly worked diligently to draft a constitution that would uphold the principles of democracy, justice, and equality for all citizens of India.