In considering what to do with the normally existing diversity in a group of children coming to a school intended for all, the concepts of integration, segregation, inclusion, and exclusion must be considered as characteristics of school aims, organization, and work. Questions related to these concepts are particularly pertinent in a discussion of special education. In the context of the Swedish schools, which are meant to be "one school for all" by parliamentary mandate, the question should be why anyone should be excluded or segregated. Regarding the issues in this light, rather than considering why someone should be included, would make the challenges for regular and special education much clearer. If real integration is the aim, then the challenge becomes accepting more diversity. Diversity in learning abilities should be regarded as something positive and valuable, rather than something to eliminate. Looking at integration in this light will mean challenges for educational research as well, since it will become more important to examine integration processes than to study bases for exclusion. It will be necessary to stop talking of integration as a method or measure and to stop referring to individuals as "integrated." Some results of a longitudinal study in Sweden show a picture of successful integration into school and later into the workforce for a group of low-ability students included in mainstream classrooms who were never designated "integrated," but who were merely included. Study of the processes that made this happen will be more useful than theorizing about inclusion. (Contains 22 references.) (SLD)