State a limit as a short sentence about what you will do, not a demand about what the other person must do, and then do it: "If X happens, I will Y."

How to do it

1. 1Identify the specific behavior, not the person's character: shouting, unannounced visits, comments about your weight, messages after ten at night.
2. 2Choose a response that is entirely within your control and that you are actually willing to carry out: ending the call, leaving the room, not replying until morning, declining the invitation. A boundary you cannot enforce alone is a request.
3. 3Say it once, calmly, ahead of time or at the moment, in the form "If you [behavior], I will [action]". Skip the history and the justification.
4. 4Follow through the first time and every time, without drama and without a lecture. Consistency is what teaches; an announced consequence that does not happen teaches that your words are negotiable.
5. 5Expect testing. People used to the old arrangement often push harder at first; hold the line on the behavior and stay warm about everything else.
6. 6Separate boundaries from punishments. The action is there to protect you, not to make the other person suffer, and it should be proportionate to that purpose.

When to use it

• •The same unwelcome behavior keeps recurring despite hints and requests.
• •Someone escalates small intrusions to see what you will tolerate.
• •You notice that you comply to avoid a scene and resent it afterwards.
• •A workplace, family, or social relationship is worth keeping but needs a limit to be sustainable.

Counters

Evidence and how strong it is

The "if you do X, I will do Y" boundary statement is a staple of clinical practice, assertiveness training, and family-recovery programs, and its components map onto tested material: clear first-person assertion (Alberti & Emmons; Speed, Goldstein & Goldfried 2018) and the interpersonal-effectiveness skills in DBT (Linehan 2015), a treatment with randomized-trial support as a package. The emphasis on consistent follow-through reflects basic learning theory: consequences that arrive intermittently maintain behavior more stubbornly than consequences that arrive reliably. The script itself, however, has not been tested as a stand-alone intervention, and the popular literature on "boundaries" is far larger than the research. Evidence strength: clinical consensus with indirect empirical support. It works best in the situation it was designed for, which is an ordinary relationship with a person who is capable of adjusting once the limit is unmistakable.

1. Linehan, M. M. (2015). DBT Skills Training Manual (2nd ed.). Guilford Press
   Interpersonal-effectiveness skills for stating requests and refusals clearly and maintaining self-respect, which the boundary script condenses.
2. Alberti, R. E., & Emmons, M. L. (2017). Your Perfect Right: Assertiveness and Equality in Your Life and Relationships (10th ed.). Impact Publishers / New Harbinger
   The distinction between assertive, aggressive, and non-assertive behavior that separates a boundary from a demand or a punishment.
3. Stark, E. (2007). Coercive Control: How Men Entrap Women in Personal Life. Oxford University Press
   The account of how controlling partners respond to assertions of autonomy, which grounds the safety caution and the distinction between boundaries and control.
4. Campbell, J. C., Webster, D., Koziol-McLain, J., Block, C., Campbell, D., Curry, M. A., et al. (2003). Risk factors for femicide in abusive relationships: Results from a multisite case control study. American Journal of Public Health, 93(7), 1089-1097
   Evidence that separation from a controlling partner is a period of elevated lethal risk.