|The present paper reports part of the findings of a participant observation study--in the role of the researcher--of a school in a large county jail. Jail school teachers, like workers in other service occupations, often confront problems when their students (clients) fail to comply with the teachers' notion of the "ideal" client. Further, given the rapid turnover of inmate students, jail teachers face a relatively fluid, unpredictable work situation. In an attempt to bring greater structure to their work situation and to cope with stress in the teacher-pupil relationship, jail teachers use typologies. They classify their students into types according to the ways in which the students affect the teachers' activities. When new students fitting one of the relevant types enters the school, the teachers are alerted to the kinds of problems that that particular type of student is likely to cause and they can then draw upon a variety of tactics or strategems to cope more readily with the problems. In the present paper, I discuss the teachers' definitions of their students as these definitions relate to the general problems of teaching, discipline, and moral acceptability. Some definitions (types) encompass all students while others differentiate among students. Further, I describe the specific problems each type of student causes for school personnel and the various ways in which the teachers attempt to cope with these problems. With respect to the general problem of teaching, jail school personnel place their students into types in terms of the ways in which the students will facilitate or hamper the teachers' teaching tasks. Relevant types include short-term students, sentenced and nonsentenced inmate students, the new inmate in jail for the first time, the inmate who has been in jail for some length of time, and the recidivist. Regarding the general problem of discipline, jail teachers define their students as passive and generally well-behaved. In contrast to the tiers where the students are housed, fights and serious disruptions seldom occur in the school. I discuss several factors which appear relevant in explaining the striking lack of discipline problems within the school. Finally, regarding the general problem of moral acceptability, the teachers define their students in terms of the ways in which the students violate the teachers' middle-class moral standards, the ways in which they differ from the teachers' conception of the "normal" middle-class student. Teachers define their students as being "free-loaders," as "worldly," as social and school dropouts, and as being more violent and brutal than inmates in the past. Further, they differentiate between those inmate students who can be "helped" -and those who cannot. Finally, some teachers differentiate between white students and black students.