In accordance with the professional plan approved by the Ministry of Culture, Sports and Tourism, from August 4 to 11, 2014, in Da Nang City, the National Library of Viet Nam organized a training course on the use of the Dewey Decimal Classification - Edition 23 in Vietnamese – DDC 23 in favor of the librarians in charge of cataloging at the information – library in the Center and Tay Nguyen Region. This is second of three courses at the North, Centre and the South. The first training course was held for library – information agencies, training institutions of the mountainous region in the North, North – West and Red River Delta had been organized in Hai Phong City in June 2014. The training course presented all important knowledge regarding the use of DDC23 which help the learners to understand the use of DDC with hierarchical structure and notations; becoming familiar with the different types of notes in DDC; to apply the basic principles for the right choice among the main potential numbers and techniques to add numbers from tables and adding tables to create classification number for a document.