Internal Family Systems (IFS)

Development from family therapy

A 2023 article in Family Process, co-written by Richard Schwartz and two family therapy educators, describes the Internal Family Systems model as developed by Schwartz from his position as a structural and strategic family therapist. The authors state that, about four decades earlier, he struggled to help clients who showed serious risk of harm to themselves or others. He began working with the positive intentions he came to see behind their harmful thoughts and behaviors, and he applied ideas from family systems thinking to patterns of internal experience.

This is an insider account, written by the model's originator and by authors who teach it, and the sources reviewed here include no independent historical study. A later research paper cites Schwartz's 1995 book Internal Family Systems Therapy, published by Guilford Press, and says the model originated in psychotherapy.

Institutions and later applications

The IFS Institute, which offers training and certification in the model, describes the research base as emerging. Its research page lists pilot studies in depression and posttraumatic stress disorder, a randomized trial in rheumatoid arthritis, and an online group program for PTSD tested at Cambridge Health Alliance. A 2017 study of healthy adults in Germany adapted the framework into a contemplative training outside psychotherapy, which shows the model being used beyond clinical settings.

Names and core terms

The model is called Internal Family Systems, abbreviated IFS. The name reflects the use of family systems thinking to describe patterns of internal experience. In a 2013 article in the Journal of Clinical Psychology, Schwartz describes a model that fosters acceptance of all of a person's parts, however destructive, and presents that acceptance as a route to transforming those parts.

A trial curriculum for an online group program describes the Self as having curious, clear and compassionate qualities. Parts are inner conflicts that are separate from the Self, and unblending means learning to separate from a part. Protectors are parts that defend the inner system, and exiles are parts that carry the burden of past trauma. These are terms of the model, and the trials reviewed did not test whether such entities exist as described.

Therapy, programs and inspired training

Research reports distinguish IFS psychotherapy from programs built on it. The Program for Alleviating and Resolving Trauma and Stress (PARTS) is an online group adaptation, and its authors note that IFS was traditionally provided in individual therapy. Böckler and colleagues describe their training as inspired by the model, not as therapy. Findings from one format should not be carried over to another.

Format and structure

Sources describe IFS as delivered in individual psychotherapy, with group adaptations in research. In the PARTS trial, each participant attended 16 weekly 90-minute online group sessions and 8 biweekly 55-minute individual sessions. The curriculum introduced the framework, then covered recognizing the Self, unblending from parts, understanding protectors, and learning to access and help exiles, and it ended with planning for continued work.

A smaller pilot for PTSD with substance use disorder used 12 weekly 90-minute groups and six 50-minute individual sessions, delivered by two licensed clinicians trained in IFS. The sources reviewed give no standard number or length of sessions for IFS delivered in private practice.

Methods within sessions

The PARTS curriculum used guided meditation, body awareness, dramatic play, insight inquiries and group discussion. It also used a center practice, in which one volunteer described internal experiences while the rest of the group watched and later discussed. The individual sessions were included to support psychological safety and to address barriers to taking part in the group.

Uses reported in research

The IFS Institute research page describes positive pilot studies in depression and posttraumatic stress disorder. Published studies have applied IFS-based interventions to depressive symptoms in college women, to PTSD in patients of a community health system, to PTSD with substance use disorder, and to rheumatoid arthritis, where the authors suggested the intervention may complement medical management. Schwartz presents the model as a way to help people accept unwanted behaviors, emotions and thoughts.

These are intended uses and hypotheses tested in small studies. They are not evidence that IFS suits any person or condition, and the research section below gives the findings and their limits as the studies report them.

Non-clinical use

In a study of 141 healthy adults analyzed from a larger German project, a three-month training inspired by the model asked people to identify and classify their inner parts. The number of parts identified was weakly associated with improvement on a theory of mind task (rho = .19, p = .046), a pattern driven by negatively valenced parts. The design was correlational, so it does not show that identifying parts caused the change, and it did not test psychotherapy.

State of the evidence

The IFS Institute states that the research base remains limited, that randomized trials with replication are needed to establish IFS as evidence-based for specific conditions, and that depression is the only condition with statistically significant improvement across multiple pilot trials. This is a concession by the training body. A 2026 systematic review of treatments for borderline personality disorder with depression or anxiety included 12 studies, and none investigated IFS.

Rheumatoid arthritis trial

A proof-of-concept trial randomized 79 adults with rheumatoid arthritis to a 9-month IFS group (39) or an education control that received mailed materials (40). After treatment, overall pain and physical function favored the IFS group (p = 0.04 for each). A year later, self-assessed joint pain, self-compassion and depressive symptoms remained improved, but anxiety, self-efficacy and rheumatologist-assessed disease activity did not. The control was not a matched group, so attention effects cannot be separated from the method.

Depression and PTSD trials

A pilot randomized 37 college women to IFS or treatment as usual (cognitive behavioral therapy or interpersonal psychotherapy). Depressive symptoms fell in both groups with no significant difference, which a sample this small cannot show to be equivalence. In a randomized trial of 60 patients with PTSD, the online PARTS program was compared with a nature-based stress reduction program. Both arms had significant reductions in clinician-rated PTSD scores with no significant difference between them, though PARTS attendance and satisfaction were higher.

Single-arm pilots

A single-arm study of 15 people reported PTSD symptom reductions with PARTS, and 53% met a clinically meaningful response by week 24. A pilot of 10 adults with PTSD and substance use disorder reported lower PTSD and craving scores, with no control group and 30% not completing assessments. Neither design can separate treatment effects from time or expectation. Funding for the PARTS work came partly from the Foundation for Self Leadership, and some authors practice IFS.

Reported harms and monitoring

The IFS Institute research page says that studies report high acceptability but that the risk of harm or adverse events needs to be systematically studied. The 2025 pilot in PTSD with substance use disorder collected adverse event reports weekly under independent oversight, and its report does not describe specific events. The sources reviewed give no frequency data for harms.

A 2026 survey of 1,507 UK adults found that 3.6% of the whole sample, and 8.9% of those who had therapy, reported recovering memories of previously unknown abuse during therapy. The author reports these were most associated with primal therapy, internal family systems and psychodynamic therapy, and raises the risk of memory construction. The data are self-reports and the abstract does not separate IFS from the other therapies, so they do not show how often IFS leads to such memories or whether recalled events occurred.

Trial exclusions and care boundaries

The PARTS randomized trial excluded people with active psychosis, a history of bipolar I disorder or active mania, severe depression, acute suicidality or self-injury, acute homicidality, severe borderline personality disorder, or illicit drug use in the previous three months. The substance use pilot excluded severe depression, psychosis and mania. These are eligibility criteria, not guideline contraindications, and the results say little about those groups.

IFS is a psychotherapy model, and this page is educational. The rheumatoid arthritis trial framed it as complementary to medical management, and urgent symptoms or crises call for conventional assessment and care, which should not be delayed or replaced.

Training and practitioner standards

The IFS Institute offers three training levels, described as primarily designed for continuing education of mental health care professionals. It states that a certificate of completion is not the same as being IFS Certified, which is a separate advanced process. The page does not say who may use the IFS name, and the sources reviewed describe no independent register. Licensure of therapists varies by country and profession and was not reviewed here.