The Constitution was issued by The Constituent Assembly, clause by clause, since November 4, 1948. Thereafter the Constitution underwent the second reading which was completed on October 17, 1949. It was followed by the third and final reading which was completed on November 26, 1949.
It took 2years 11months and 17days for The Constituent Assembly to finally pass the Constitution.
The date January 26, 1950 for commencement of the Constitution was specially selected for its historical importance. It was on this date, January 26, 1929 that the Lahore Session of The Indian National Congress had for the first time given the call of Purna Swaraj or Complete Independence.
Since then the day was celebrated as Independence Day upto 1947.