ABSTRACT: This study falls within the field of research focused on teacher training, aiming to understand how these professionals are trained in a collective context, such as a study and research group. This article presents an interpretation of actions carried out in a study and research group, which, based on certain principles, can guide the teacher training of the participants. The intention is to view this training from the perspective of activity, based on the premise that a collective study and research group that emphasizes actions beyond its structural dimensions offers training that, with new qualities, transforms the individuals involved. Thus, a research was developed based on the premises of Historical-Cultural Theory, with the objective of understanding the principles that guide teacher training in a collective. Data were produced through the analysis of actions carried out in a study and research group with 18 members, comprising undergraduate students, teachers pursuing postgraduate studies, and/or teachers from Basic Education or Higher Education participating in its projects. The analytical process, grounded in the dialectic between the guiding and executing dimensions, sought to identify guiding principles of teacher training in the group through the various actions it develops. The results indicate that these actions allow the principles to be actualized, facilitating the formation of individuals from the perspective of a collectivist personality, based on the affective-cognitive unity constituted in the process of participating in the group/collective, which can contribute to the personality development of the individuals involved.