Officials including the President Iajuddin Ahmed and Prime Minister Khaleda Zia gathered at midnight Tuesday to place wreaths at a shrine known as the Central Shaheed Minar.
The ceremony marks protests in 1952 by students and others who opposed a policy by the government at the time that made Urdu the official language of the country then called Pakistan.
A bloody crackdown on the demonstrators sparked an uprising that years later led to Bangladesh's split from Pakistan.
In 1999, the United Nations Cultural Organization UNESCO designated February 21st as International Mother Language Day, dedicated to promoting linguistic diversity and multilingual education.
Matiur Rahman Choudhury has more on the story.