The work of investigating, collecting and systematizing documents on customary laws and ethnic conventions in Vietnam is being meticulously carried out. This book reviews some of the issues that have been raised during the study of customary laws of ethnic groups. This work consists of 11 chapters, can be divided into two parts. Part 1 examines various aspects of customary law, such as the approach to customary law; origin and nature of customary law; forms of development of customary law; the content of customary law; the enforcement of customary law; validity of customary law; customary law and national law. Part 2 introduces the customary laws of some ethnic groups such as the Ede, M'nong, Thai and Vietnamese conventions. They are considered as representatives of the different forms and levels of development of customary laws of ethnic groups in Vietnam.