Case studies of low ability Third Year classes were carried out in four schools selected from a representative sample of Inner City secondary schools taking part in a major research project concerned with underachievement. The four schools represented a contrastive sample on the basis of the different percentages of their pupils (between 33% and 72%) expressing the wish to stay on in school after the Fifth Form. The schools' state examination results were also very divergent. A symbolic interactionist perspective was adopted and the focus of the research was on teacher/pupil interaction, and in particular on the language of the classroom and the kinds of conversational opportunities teachers left open for their pupils. The research methodology was that of 'combined levels of triangulation': information at the level of the school, the class group and the individual teacher and pupil was gathered in order to further understanding of classroom interaction. Discourse analysis was used to analyse transcripts of tape-recorded classroom talk. Teacher, pupils and researcher each contributed to the evaluation of classroom process; written work produced as a result of the lessons was also examined. Four research questions were addressed: 1: Does the same class of low ability adolescents behave differently with different teachers. 2: Does the same teacher behave differently with different classes. 3: What kind of classroom interaction is favoured by teachers. 4: What are the effects of different types of classroom interaction on pupils' interest and work levels. It was found that the same class behaved very differently with different teachers, but that features of the teacher's self-presentation and teaching style changed little across classes. Teachers preferred classes which they could control well and in which there was a close match between their most cherished professional skills and the class's needs. Such classes confirmed their professional self esteem. The sensitive management of interpersonal relations proved crucial to a teacher's success with low ability groups. Such pupils presented their teachers with particular problems of control in 'whole class' discussion of a freer kind: they lacked necessary discourse skills, and (particularly in more traditionally- run schools) behaved as if they did not see such opportunities as legitimated learning situations. This caused some teachers to restrict class discussion to highly structured and relatively unchallenging teacher- question pupil-answer sessions. However where the teacher could supplement this kind of interaction with interludes in which pupils' contributions were not limited to such responses, valuable learning opportunities were seen to result. Teachers who could approach potential challenges to their control of the situation as exhilarating rather than merely stressful were more likely to persevere in encouraging this type of pupil participation. Implications of research findings for practising teachers were discussed