This paper identifies the theoretical, constitutional and practical basis for land acquisition in Vietnam from a comparative perspective. Both the ideology based on private ownership and the ideology based on public interests are reviewed in order to explain the grounds to request compulsory acquisition. By studying the constitutional provisions relating to compulsory land acquisition in some relevant countries, and exploring the provisions on land acquisition determined in Vietnamese Constitution in the case of national defense, security and socio-economic development, this article analyzes some key themes of purposes, procedure and compensation. On that basis, comments on legal improvement are suggested to complete Vietnam Land Law in the future.