Background: Appropriate supports and instructional practices contribute to the development of self-determination. Also, research shows that the promotion of skills related to self-determination has been linked to the achievement of desired outcomes over the different life stages. Advances in self-determination require the development of assessment instruments because there is a reciprocal relationship between assessment and instruction. The purpose of this paper is to provide a description of the AUTODDIS Scale, along with evidence of its reliability and external validity. Method: A sample of 541 people with intellectual disabilities aged from 11 to 40 was used to validate the scale. Results: The reliability results indicate that the AUTODDIS Scale shows high internal consistency. The total score and subscale scores indicate moderate inter-rater reliability. The scores were also moderately to highly associated with other related measures of self-determination and quality of life (QoL). Conclusion: Our results demonstrate that consistent and valid information can be obtained from the AUTODDIS Scale.