Background: Autonomy support in people with intellectual disability (ID) is an important yet understudied topic. Psychometrically sound instruments are lacking. This study tested the factor structure and reliability of an instrument for assessing the extent people with intellectual disability perceive their support staff as autonomy supportive. Method: In a single wave, 185 adults with mild-to-borderline intellectual disability filled in an adapted version of the Health Care Climate Questionnaire (i.e., HCCQ-ID). Forty of them participated in a second wave to determine test-retest-reliability. The HCCQ-ID consists of 15 items on a 5-point Likert scale. Results: The expected one-factor structure was found. Internal consistency (a = 0.93) and test-retest reliability (r = 0.85) were good. The score distribution was skewed towards high satisfaction. Conclusions: The factor structure and reliability of the HCCQ-ID were supported for people with mild-to-borderline intellectual disability. Given the homogeneous factor structure and the high reliability, the number of items may be further optimized.