This study investigated the main psychometric properties of the Self Assessment and Intervention (SAINT), a unique and recently developed Guided Self-Help tool for people with intellectual disabilities (ID). Fifty-four adults with ID identified with symptoms of anxiety and/or depression completed the study. They were between 18 and 77 years old with a mean of 39.4 years of age (SD = 13.57). Participants were recruited from both community (n = 31, 57.4%) and inpatient settings (n = 23, 42.6%). The Glasgow Depression Scale-Learning Disabilities (GDS-LD) and Glasgow Anxiety Scale-Intellectual Disabilities (GAS-ID) were used as expert measures. Convergent validity, concurrent validity, test-retest, and internal consistency were all tested on the SAINT in comparison with the GDS-LD and GAS-ID as appropriate. There were no missing data from the questionnaires. Cronbach's alpha suggested high internal consistency for the SAINT questionnaire at 0.827 and interitem correlation for internal consistency of the SAINT for any item deleted ranged from 0.788 to 0.826. In terms of convergent validity using the Spearman's Rho correlation coefficient the SAINT showed significant correlation at the 0.01 level (2-tailed) with the GDS-LD (r = 0.707), GAS-ID worries subscale (r = 0.578). The correlation for test-retest (n = 20, 37%) between Time 1 and Time 2 was r = 0.897, p less than 0.01. The SAINT has demonstrated potential as a measure for investigating mental distress for people with ID. One of the unique benefits of the SAINT is that it has a different utility from other measures used in this study that focus on psychopathology. The SAINT has not been designed as a diagnostic tool and aims to get the person to recognize and report a set of symptoms that indicates mental distress and to employ coping strategies once identified. (Contains 1 figure.)