According to the study of the cultural assimilation of Phu-Thai and Thai-Lao people, it is found that the language assimilation, the four necessities, the religion, the traditions and the rituals are a result of the Phu-Thai’s cultural assimilation process receiving both Thai-Lao and Central Thai culture through daily interaction between the Phu-Thai and the Thai-Lao. The wider culture of the Thai-Lao, the majority group in the Northeast, has causes the Phu-Thai to adopt this culture in their society such as the similar characteristics of their languages and the similar religious practices following traditions and lifelong rituals -birth, wedding and the belief of their ancestors’ spirits. At the same time, the Central Thai’s culture has also influenced the original culture of both. It has caused many changes in their cultures, for example the changes in their areas – they have replaced their original cotton and silk with modern-fashion clothes and their dwellings – the two ethnic groups prefer to build modern-style houses and separate their families from their parents’ . For illness treatment, both ethnic groups now prefer to be treated at the health centers and hospitals. Some rituals have been changed such as their weddings– they hold their wedding ceremony in the cultural style of Central Thai’s. Although, there is local cultural assimilation of the Phu-Thai and Thai-Lao people, the international cultural assimilation of the Phu-Thai and the cultural assimilation of theThai-Lao with Central Thai, the Phu-Thai people have been able to maintain their cultural identity for example in their wedding ceremony. Even though they have adopted the Central’s Thai’s culture in their wedding ceremony, there are still their traditional Por Lam and Mae Lam in the ceremony. For this reason, at the present, the Phu-Thai is still an ethnic group which can live together with Thai-Lao, the majority group in the Northeast. (page 157-162)