Summary.Teacher‐pupil interactions were observed in the classrooms for a four‐month period to determine similarities and differences in teacher‐pupil interactions of problem and non‐problem children. Analyses of 15 teacher and pupil process measure variables were conducted to assess the stability of teacher‐pupil interactions in a number of relevant behavioural measures and to determine the development of any clear trends in teachers' interactions with problem and non‐problem children. Results suggest that a certain deterioration is noticeable in teachers' interactions with problem children receiving more negative affect and less sustaining feedback from their teachers over the course of four months. Observations of problem children's behavioural interactions suggest an increase in serious misdemeanours and a corresponding decline in sustained attention. Educational implications of the study are discussed in terms of the mental health needs