HD is a complex disorder in which there is relentless deterioration of motor, cognitive and behavioural functions, usually from mid-life onwards. The original CAPIT battery aimed to capture elements of change in all three domains, but was based predominantly on subjective semi-quantitative assessment tools that have poor inter-rater reliability. Moreover, a number of deficits, such as impairments in social cognition, were not recognised when the original CAPIT-HD battery was constructed, so we have developed novel assessments of these deficits, some of which are included in CAPIT-HD beta. The beta testing will take place in established HD clinical centres in Cardiff, Manchester, Paris, and Munster by teams of researchers who are experienced in leading clinic research in HD. Patients with early to moderate HD will be assessed at baseline, and at one and twelve months later, to assess the reliability and sensitivity of the CAPIT-HD beta battery. Arrangements for data storage and analysis are in place.