Welcome to the workshop on ethnic groups in Southeast Asia. We will start with introductions from the participants; this workshop is structured so as to promote the methodological and pedagogic dimension, and exchanges and discussions will be a priority all week. Presentation of the trainers and participants (see biographies of trainers and list of participants at the end of the chapter) How will these four and a half days of group work unfold? We will devote this first day to the ways in which ethnic groups are designated and named, and our approach will initially be theoretical and methodological: we will explain the constructivist and naturalist approaches. We will ask what an ethnic group is and how and why we make ethnic classifications. In the afternoon, we will turn towards case studies in Việt Nam and in Laos. Tuesday will be devoted to the relationship between the law and ethnic groups. We will start with the legal situation so as to be able to observe the relationship with what is visible in the field. Sociologists and anthropologists use the law very rarely as an instrument of knowledge; we will try to establish a relationship between law and anthropology. We will conclude this second day with case studies. Questions from applied anthropology and development anthropology will be studied on Wednesday morning, then we will together organize three working groups, one group per trainer with a specific theme. Friday morning will be devoted to presentations from each group; from these we will derive a synthesis for the public reporting session on Saturday.