Patients who are referred for possible bariatric surgery (BS) intervention undergo a series of assessments conducted by an interdisciplinary health care team to determine suitability for surgery. Herein, we report the initial validation and reliability studies of the Bariatric Interprofessional Psychosocial Assessment Suitability Scale (BIPASS) and its relationship to interdisciplinary psychosocial assessment practices for BS. This study was conducted at the Toronto Western Hospital, a Level 1A BS center of excellence accredited by the American College of Surgeons. Phase I: a total of 4 blinded raters applied the BIPASS to 31 randomly selected BS cases referred to our program to establish interrater reliability. Phase II: in all, 3 raters with clinical experience in bariatric psychosocial care applied the BIPASS to 54 randomly selected BS cases. In total, 46 of 54 (85.1%) patients were women. The median age of all patient cases was 49 years (range: 21-74). Raters׳ BIPASS scores ranged from 4-52 (median = 19.24, standard deviation =10.38). BIPASS scores were highly predictive of the BS psychosocial outcome (area under curve = 0.915; 95% CI: 0.844-0.985; p < 0.001). A BIPASS score of ≥16 was chosen as the cutoff score for further clinical assessment before proceeding with surgical evaluation based on a receiver operating characteristic curve analysis (sensitivity = 0.839; specificity = 0.783). The instrument has very good interrater reliability (Pearson correlation coefficient = 0.847) even among novice raters. The findings show that the BIPASS is a comprehensive screening tool in the psychosocial assessment of BS candidates, which standardizes the evaluation process and systematically identify at-risk patients for negative outcomes after BS.