In the case of individual psychotherapy, two persons participate in the sessions and consultations: the psychotherapist and the patient.
As for couples psychotherapy, depending on the problem of the couple and the particular approach of psychotherapy sessions and consultations may be attended by one or two psychotherapists meeting with the couple.
In the case of family psychotherapy in the office may appear not one, but even two or more generations of a particular family, people with different degrees of kinship. In the case of educational problems, it is often parents with children or a child. Family psychotherapy can be conducted by either one or a couple of psychotherapists.
In the case of group psychotherapy, the number of people varies most often from several to several dozen. Here, it may also happen that one or two psychotherapists will be present, depending on the proposed approach, the problem of the group, the age range and the number of participants.
In specific cases-which I will not describe in detail here-the number of people directly participating in sessions and consultations on the part of the leaders may be greater, for example: in institutions that undertake training of psychotherapists.