The key difference is whether new members are admitted after the work begins. Members of a closed group usually start together and no new people join after the agreed entry point. An open group accepts new members when places become available, so its composition changes over time. Neither format is inherently better. The choice depends on the purpose of the group, the length of the programme, its rules, and whether you value a stable membership or the option to start sooner.
An open group does not mean casual attendance without preparation. A responsible facilitator still holds a preliminary conversation, explains the agreement, and considers whether the format is suitable for the person.
How a closed group works
A closed group enrols members for a particular start date. Entry then stops, or remains possible only during a brief introductory period. The number of meetings and the end date are often known in advance, although some closed groups run for longer.
A stable membership allows people to get to know one another gradually and notice how relationships develop. The facilitator does not have to repeatedly introduce new members to work already in progress. This can be particularly useful in programmes with a sequence of topics or exercises.
There are limitations. You may have to wait for the next group to begin. If several people leave, the facilitator cannot always replace them and the group may continue with fewer members. A missed session usually cannot be made up with another cohort, so it is worth checking the attendance policy in advance.
How an open group works
New members can join an open group when a place becomes available. There may be no shared end date: each person joins and leaves at a different time, discussing the ending with the facilitator. Agreeing on arrangements for leaving does not mean you need permission to leave.
This format may make it possible to begin without waiting for a new intake. Welcoming newcomers and saying goodbye to departing members also become part of the actual group process. Members practise meeting people, tolerating change, talking about endings, and rebuilding trust after the membership shifts.
At the same time, changes can bring anxiety or fatigue. The facilitator should prepare a new member, remind everyone about confidentiality, and make room for reactions to arrivals and departures. New people appearing without any explanation of the agreement is not simply a feature of an open group; it is a reason to ask how the group is being led.
Clarify the intake arrangements
The American Group Psychotherapy Association's professional guidelines treat member selection and preparation as important facilitator responsibilities. Before joining, a person should be able to discuss goals, expectations, the limits of confidentiality, fees, and how endings are handled. An available place should not replace informed participation.
Ask what the organiser means by “open group.” It may be a long-term therapy group with a screening interview, a short programme with several entry points, or a support meeting that permits drop-in attendance. These formats have different aims and different levels of continuity.
“Semi-open” also needs explanation. For example, a programme might admit new members only between modules and keep membership stable within each module. Ask about duration separately: an open intake and an open-ended duration are different features. A group may admit newcomers and still finish on a set date.
How to choose between the formats
- A closed group may suit you if a stable membership, a shared beginning, and a clear programme with an end date matter to you.
- An open group may suit you if starting sooner matters, you are prepared for membership changes, and individual decisions about ending feel acceptable.
- Do not judge by the intake model alone. The facilitator's competence, the purpose of the group, its safety agreement, and the fit with your needs matter more than one label.
If membership changes feel especially frightening, mention this during the initial conversation. It does not automatically mean that an open group is unsuitable. The facilitator's answer can show how newcomers are prepared and how the group is helped to process change.
Questions to ask before enrolling
- Is the group open, closed, or semi-open?
- When and under what conditions can new members join?
- Is there a fixed number of sessions?
- How is a new member introduced to the rules and agreements?
- How does the group address arrivals and departures?
- What happens if membership becomes too small?
- How do absences, payment, and ending participation work?
For broader safety criteria, see “How to choose a therapy group and facilitator”. Preparation for the first session is covered in “Your first group therapy session”.
Red flags are not determined by the group type
Be cautious if the organiser cannot explain the purpose and rules, guarantees results, admits people to intensive therapy work without any preparation, or cannot say how confidentiality is protected. In an open group, it is particularly important to understand who introduces new members to the agreement and how this is done.
Key point
A closed group stops admitting newcomers after the agreed entry period; an open group accepts people as places become available. A closed format offers more predictability, while an open one offers more flexibility. Quality depends not on the label but on clear selection, preparation, boundaries, management of change, and endings.
Sources
- American Group Psychotherapy Association: Practice Guidelines for Group Psychotherapy
- AGPA: Ethics in Group Therapy
This article is for general information. The agreement of the particular group determines its enrolment, payment, and ending arrangements.