DescriptionDialectical behavior therapy (DBT) is a treatment for Borderline Personality Disorder (BPD) that includes specific strategies a therapist can use to direct treatment. Of these strategies, validation is considered to be the most direct method for communicating acceptance, is proposed to lead to a down-regulation of a problematic emotional response, and is important to consider in treating population characterized by emotional dysregulation. While validation is implicit in many therapies, DBT is one of few treatments to explicitly include six validation strategies. Little research has been conducted to examine how validation is used in therapy and no studies have examined the six levels of validation in DBT. One major limiting factor is the lack of measures designed to assess validation strategies. The DBT-Validation Level Coding Scale (DBT-VLCS) was designed bridge this gap and code for the use of the six validation levels (VL). Two studies were conducted to determine the preliminary psychometric properties of the DBT-VLCS. Results demonstrated that reliability was good for the complete measure (ICC= .905), VL 1 (ICC= .771), VL 2 (ICC= .738), VL 3 (ICC=.623), VL 4 (ICC= .914), VL 5 (ICC= .836), VL 6 (ICC= .831), and an item coding perceived client response (ICC= .900) for all raters. Content validity of the DBT-VLCS was examined through a survey distributed to expert DBT clinicians. The measure achieved good content validity for VLs 1 through 4, VL 6, and the item coding perceived client response. The item coding VL 5 did not achieve good content validity. Overall, the DBT-VLCS appears to be a reliable and valid measure to code the presence of therapist use of validation within an individual DBT treatment session. This measure opens up the opportunity for research on validation that has not previously been possible, including how to increase the effectiveness of DBT for clients with significant emotional dysregulation through the strategic use of therapeutic strategies.