Marriage always plays an important part of one's life, of each family and of the whole society. That is not an exception for the Lach people - a group of local residents of the Co ho ethnic group in the Central Highland, Vietnam. Marriage ceremonies in this group have been "institutionalized" by Nri (Customary Law) - rules adjusted, accepted by or based on the customs and practice of people in a society. Through customary law, it appears that the traditional marriage of the Lach people has many unique features such as the custom of challenging wedding gifts, marrying the family member(s) of the deceased husband, asking man's parents for permission to marry, staying with wife's family, etc. Nevertheless, due to the significant changes of society in recent years, the customary law in marriage of the Lach people has been changing considerably as a result.