Access to public education is a democratic right for every person living in Sweden. Schools are obliged to meet the needs of all individuals and provide high quality education for everyone. This implies that the institution has to deal with diversity in a very obvious sense, Differences between children in their behaviours, attitudes, intellectual and social skills, physical ability, cleanliness, ‘moral character’ and so on have been pragmatic issues that have been attended to ever since the public schooling started in the 19th century. However, some pupils have difficulties in adapting to life in school, and schools continuously have to handle dilemmas in this respect. This implies that schools have to develop certain institutional practices in response to such problems in order to prevent school failure and in order to handle various concrete dilemmas. In this process categorization has become a necessity in the process of bringing order to the daily practices. In fact, the activity of classifying and categorizing children is “as old as schools themselves”, as Mehan (1993, p. 243) puts it. In this paper I will give a brief historical review of categorizing practices in a school for all in Sweden