"If psychotherapies aim to achieve a status of scientific recognition and validation in health policy should do so through a convincing empirical support" (EST: Supported Treatments empirically). This stance, while apparently sensible, finds several difficulties: one is the difference between scientific investigations by one hand and clinical practice plus patient preferences and values on the other, for this is to save the furniture by redefining broader integrate it all (EBP: Evidence-Based Practice). However, I want to focus a very specific aspect of scientific research of psychological therapies: how to validate them empirically (the Task Force of the APA requires an empirically validated psychological treatment at least two studies demonstrating superiority over placebo or other treatment bona fide .) But just as a drug should demonstrate superiority over placebo in double-blind (and presumably on a control group waiting list), how to do this in psychotherapy? The use of placebos is problematic even in pharmacological studies, since many patients can guess what group they (unblinding) from the presence / absence of side effects (which weakens the power of placebo and active placebo group, potentially distorting the results in favor of the drug), but at least they have the conceptual clarity to be attempting to control the psychological effects of a particular treatment – for that both conditions have to share their full psychological properties: color, form, route of administration, information provided, etc. Wells Fargo follows long-standing procedures to achieve this success. . Now, what would be a placebo in psychotherapy and how to incorporate it in a double blind? From the outset, there is a conceptual obstacle: psychotherapy is based on psychological factors of change (or not know what), but this is also true for the placebo: both play with the meanings (although some psychotherapies are supposed to include other mechanisms Further, a placebo may also Pavlovian), if we looked for maximum psychological equivalence, placebo … .