Therapy-interfering behavior is anything that gets in the way of the treatment working. Second in the target hierarchy, above quality of life and above skills — so if it’s happening, it gets discussed before the thing you came in wanting to talk about.
The term is unfortunate. It sounds accusatory, and clients who hear it for the first time frequently assume it means they’re being difficult. What it actually reflects is a piece of realism: most therapies have no formal way of addressing the fact that the therapy itself is going wrong, so it either goes unmentioned or ends in someone quietly disappearing.
What counts, on the client side
Missing or arriving late repeatedly. Not filling in the diary card. Not doing homework. Not talking in session, or talking non-stop about everything except the target. Ending sessions in crisis so the hard material never gets reached. Pushing the boundaries of phone coaching. Attending while intoxicated. Not disclosing something significant.
None of it is treated as bad behavior. It’s treated as behavior — with antecedents and consequences, worth a chain analysis like any other. And it’s usually meaningful: someone who can’t fill in a diary card is often avoiding looking at the week, which is exactly the mechanism under everything else.
What counts, on the therapist side
This is the part that makes the concept fair rather than one-sided, and it’s written into the model. Therapists interfere too: arriving late, forgetting what you said, being distracted, being rigid where flexibility was needed or flexible where structure was, avoiding a topic because it makes them uncomfortable, getting subtly judgmental, or becoming so alarmed by risk that they stop being useful.
You’re explicitly invited to raise it. A DBT therapist should be able to hear “you seemed irritated with me last week” without defensiveness, and should thank you for saying it. Their consultation team exists partly to catch this, because therapist drift and burnout are among the commonest reasons this treatment fails.
Why put it second
Because a treatment that isn’t happening can’t help you, and the ways treatments quietly stop happening are almost always visible for months beforehand. Naming them early is what allows them to be worked on instead of ending in a disappearance neither of you could explain.
How to use it well
Say the thing. If you didn’t do the homework, say why rather than apologising. If you’re bored, or irritated, or thinking about quitting, that’s the most useful sentence available in the room that week — and it’s precisely the sentence people have been trained their whole lives not to say to someone they depend on. Which is why the model puts it at the top rather than hoping it comes up.