Director Josip Stipanov said the NSK was an institution which best confirmed Croatia's national identity and testified to its continuity whose origins went back to a 1607 Jesuit conference in Zagreb.
Speaking on the government's behalf, Culture Minister Bozo Biskupic recalled the history of librarianship in Croatia, beginning with Roman Emperor Diocletian's palace in Split, and said the NSK was a bridge between a historically rich past and the requirements of the contemporary information society, as evidenced by its membership of the European Library since 2005.
Biskupic said the creation of a European Digital Library prompted the NKS to connect with archives and museums both at home and internationally.
The sponsor of the celebration, President Stjepan Mesic, said the NSK housed works which were the foundation of Croatia's national culture and science.
"The challenges of the new, digital age and the accelerated development of information technology have transformed over the past dozen years the treasury of the Croatian written word into a dynamic window into the future which has been Croatia's strategic goal for 15 years," said Mesic.
The future of contemporary Croatia is in united Europe in which we will all be equals in standards and laws but different in languages, cultures and identities, Mesic said, adding that contemporary Croatia should not and must not turn its back on its national identity and legacy.
Mesic said that for small countries like Croatia investing in the future and science were prerequisites for a faster economic development and integration with the global market, and that culture was an opportunity to present and not lose oneself.
"European institutions are aware of that too, strongly pushing culture to the centre of the European project and underlining, as stated in European Commission documents, that it is culture that can breathe a more human dimension into the European integration project," said Mesic.
He also remembered a number of people who he said had used their political influence to have the current NSK building built.
Two exhibitions were opened and a monograph was published to mark the anniversary.
Last year the NSK logged more than 30 million visitors and more than 500,000 Internet hits, said the director.