Background: The school environment has shown itself to be an important factor in explaining adolescent behaviour. The relationships and experiences that pupils have at school have been found to influence their development, psychological well-being, self-esteem and social adjustment. Purpose: The aim of the study is to explore whether there is a relationship between pupil-peer and pupil-teacher relationships and psychological well-being and self-esteem, and whether this relationship varies according to pupils' experience of bullying or being bullied. Sample: Data consisted of a sample of 3694 students (mean age?±?SD 14.3?±?0.62 years; 51% girls) from elementary schools in Slovakia. Design and method: Questionnaires were administered to the students. In terms of data analysis, linear regression was firstly used in the whole sample to explore pupil-peer and pupil-teacher relationships and psychological well-being (the depression/anxiety and social dysfunction subscales of GHQ-12) and self-esteem (positive and negative self-esteem subscales of RSE). Next, the whole sample was divided into four groups in terms of involvement in bullying (normative contrasts, passive victims, aggressive non-victims and aggressive victims). Linear regression was used to explore the associations between pupil-peer and pupil-teacher relationships with the two factors of psychological well-being and two factors of self-esteem in these four groups. Results: As findings showed, better pupil-peer relationships and also pupil-teacher relationships were significantly related statistically to less depression/anxiety and social dysfunction, as well as to more positive and less negative self-esteem. All bullying categories were significantly related to pupil-peer relationships and the four dependent variables. However, in the categories of aggressive victims and aggressive non-victims, the pupil-teacher relationship was not significantly related to their psychological well-being and self-esteem. Also, in all subgroups, better pupil-peer relationships were significantly related to less depression/anxiety and social dysfunction, as well as with more positive and less negative self-esteem. Conclusion: Given the differences found in the connections between pupil-teacher relationships and well-being and self-esteem, between those who bullied and those who were bullied, it would seem that the school environment can play an important role in implementing anti-bullying prevention strategies.