What a decade of parts-informed work taught me about EMDR, including when to leave parts work out

By Timothy Vermillion, DSW, LCSW – EMDR Consultant and Trainer

About a decade ago I took one of Carol Forgash’s workshops on integrating ego state work with EMDR, and it changed how I think about trauma. Her book with Margaret Copeley, Healing the Heart of Trauma and Dissociation with EMDR and Ego State Therapy, became foundational for me, and over the years I added Anabel González and Dolores Mosquera’s EMDR and Dissociation: The Progressive Approach, and The Haunted Self by Onno van der Hart, Ellert Nijenhuis, and Kathy Steele. Together they gave me a real appreciation for the place of parts in treating PTSD and the more complex dissociative presentations.

So it is from inside that tradition, not outside it, that I want to make an argument that sounds almost contrarian: EMDR is often helpful without integrating parts work at all, and the various things people call “parts work” are not one method resting on one theory. The word is a useful umbrella. It is not a protocol.

What “parts” is doing in the sentence

Sit in enough case consultations and you hear it constantly. A clinician says EMDR “got blocked by a part.” A client mentions their therapist is “blending EMDR with parts work.” Someone describes an ego state, a protector, a dissociative compartment, and an Internal Family Systems exile as if they were the same furniture in the same room. They are not. “Parts” has become a shared vocabulary stretched across several distinct models: ego state therapy, IFS, the structural theory of dissociation, and the loose everyday sense of feeling internally divided. The word travels easily. The theories underneath it do not.

EMDR doesn’t always require a parts overlay

Here is the part that matters most for everyday practice. Standard EMDR, organized around the Adaptive Information Processing model, is an established treatment for PTSD in its own right. For many appropriately assessed PTSD clients, processing the disturbing memory networks toward an adaptive resolution is the work, and a parts overlay is not required. That is not the same as skipping the fundamentals: screening, readiness assessment, stabilization, and consultation still matter in every case. What it means is that ego state mapping, parts negotiation, or dissociation-specific scaffolding are not automatically necessary for every PTSD presentation. When I teach, I try to keep newer clinicians from concluding that good trauma work always requires a parts framework layered on top. Often it does not, and adding one where it isn’t indicated can complicate a course of treatment that would have moved cleanly.

Where parts-informed work earns its place

The exception, and it is an important one, is complex trauma and dissociation. With clients whose histories have left the personality more divided, asking them to process a full traumatic memory too early can destabilize rather than heal. This is exactly the problem Forgash’s ego state integration and González and Mosquera’s Progressive Approach were built to address: prepare and stabilize first, titrate the approach to the trauma, and respect the dissociative structure rather than bulldozing through it. In significant dissociation or complex trauma, phase-oriented preparation, stabilization, and attention to dissociative structure can become central to sequencing the work safely. The skill is knowing which client is in front of you.

The models don’t share a theory

This is where precision really matters, because the differences are not cosmetic.

The Adaptive Information Processing model is, at bottom, a model of memory. It assumes a single, intrinsic, healing-oriented processing system; it locates distress in dysfunctionally stored, unprocessed experience; and it understands recovery as reprocessing that material toward an adaptive resolution. In a strict AIP reading, what looks like “a part” is better understood as a state-dependent memory network.

Internal Family Systems begins from a very different premise: the non-pathological multiplicity of the mind. In IFS the psyche is natively composed of parts, together with a core Self, and the work is a Self-led relationship with those parts rather than the reprocessing of a memory. That is not a different technique for reaching the same destination; it is a different account of what a person fundamentally is and what healing means.

And the structural theory of dissociation, van der Hart, Nijenhuis, and Steele, is different again. There, parts are trauma-generated divisions of the personality, an apparently normal part oriented to daily life alongside emotional parts fixed in trauma. That is a pathology- and trauma-based model, and it is conceptually distinct from IFS’s idea of an innate, healthy multiplicity. The ego state and Progressive Approach work I rely on lives in this structural lineage, which is precisely why I bristle a little when it gets folded into “IFS” as though they were interchangeable. These are different, and not interchangeable, starting assumptions about whether multiplicity is the wound or the design.

A note on the evidence

I’ll be candid that the research has not fully caught up to the clinical enthusiasm here. We have a deep case literature, influential clinical texts, and group-format work on the Progressive Approach, but I am not aware of controlled head-to-head trials showing that adding parts-informed interventions to standard EMDR improves or worsens EMDR outcomes compared with standard EMDR alone. There is emerging trial work on IFS-derived treatment for PTSD (the PARTS study), but that speaks to the feasibility and acceptability of an IFS-based PTSD treatment; it does not answer the EMDR-integration question. I hold my own integration of these approaches as clinically reasoned and, in the right cases, clearly humane, not as something a trial has settled. That gap is worth naming honestly, and it is worth studying.

Why the distinction is worth keeping

None of this is a turf war. Parts language is genuinely valuable: it gives clinicians and clients a humane way to talk about internal conflict, and in complex cases attention to parts and structure can be the difference between sequencing the work safely and flooding someone. But it earns that value only when we keep the words honest, when “parts” is allowed to be the friendly umbrella it is, and the distinct models under it (Adaptive Information Processing, ego state therapy, the structural theory of dissociation, Internal Family Systems) are each allowed to mean what they actually mean. The point is not to choose EMDR or parts work as an ideology; it is to match sequencing, stabilization, consultation, and method to the client in front of us.

References

Shapiro, F. (2018). Eye Movement Desensitization and Reprocessing (EMDR) Therapy: Basic Principles, Protocols, and Procedures (3rd ed.). Guilford Press. [Adaptive Information Processing model]

Schwartz, R. C. (1995). Internal Family Systems Therapy. Guilford Press. [Non-pathological multiplicity of mind]

van der Hart, O., Nijenhuis, E. R. S., & Steele, K. (2006). The Haunted Self: Structural Dissociation and the Treatment of Chronic Traumatization. W. W. Norton.

Forgash, C., & Copeley, M. (Eds.). (2008). Healing the Heart of Trauma and Dissociation with EMDR and Ego State Therapy. Springer Publishing.

González, A., & Mosquera, D. (2012). EMDR and Dissociation: The Progressive Approach. Amazon Imprint.

González-Vázquez, A. I., Rodríguez-Lago, L., Seoane-Pillado, M. T., Fernández, I., García-Guerrero, F., & Santed-Germán, M. A. (2018). The Progressive Approach to EMDR Group Therapy for Complex Trauma and Dissociation: A Case-Control Study. Frontiers in Psychology, 8, 2377. https://pmc.ncbi.nlm.nih.gov/articles/PMC5816929/

Joss, D., Comeau, A., Chevannes, R., Parry, G., Rea, H. S., Barria, J., Bumpus, C., Rector, A., Rajan, A., Rosansky, J., Rice, F. K., Ward, M. C., Tobiasz Veltz, L., Ally, D., Rosenberg, L. G., Sweezy, M., Lovas, D., & Schuman-Olivier, Z. (2026). A randomized controlled trial of an online group-based internal family systems treatment for posttraumatic stress disorder: The Program for Alleviating and Resolving Trauma and Stress (PARTS) study. Psychological Trauma: Theory, Research, Practice, and Policy. https://pubmed.ncbi.nlm.nih.gov/41609644/

Ally, D., Tobiasz-Veltz, L., Tu, K., Comeau, A., Bumpus, C., Blot, T., Rice, F. K., Orr, B., Soumerai Rea, H., Sweezy, M., & Schuman-Olivier, Z. (2025). A pilot study of an online group-based Internal Family Systems intervention for comorbid posttraumatic stress disorder and substance use. Frontiers in Psychiatry, 16, 1544435. https://pmc.ncbi.nlm.nih.gov/articles/PMC11983591/