Background: Many standardised balance measures are unsuitable for people who are unable to comprehend test requirements. We report on the development, administration, interrater reliability, and concurrent validity of a video-based balance measure for people with intellectual disability called the Balance Scale for Persons with Intellectual Disabilities. Method: Video recordings of 25 people performing 7 common motor tasks, identified from stakeholder consultation, were made, and rated using standardised scoring criteria. Concurrent validity, assessed against the Tinetti Gait and Balance Instrument and the modified Gait Abnormality Rating Scale (GARS-M), and interrater reliability of the scale was evaluated with 19 physiotherapists. Results: Scores suggested no ceiling or floor effects. Excellent interrater reliability (ICC = 0.9) was demonstrated. Concurrent validity was good against the Tinetti (? = 0.98) and the GARS-M (? = -0.87). Issues around lighting for video-recording and lack of steps or stairs in the home setting were encountered. Conclusion: The new measure may be useful in trials assessing the effectiveness of interventions aimed at improving the balance capabilities of people with intellectual disability.