A grant of £310,143.98 over 28 months to conduct a Randomised Controlled Trial (RCT) of the InDEx smartphone application (app) to assess if it is effective in reducing alcohol consumption of veterans who drink at hazardous levels and are receiving, or have received, support for mental health symptoms in a clinical setting. Secondary aims are to assess the impact of InDEx on the quality of life of veterans, and to evaluate the benefit(s) to using digital technology in supporting service charities and the veteran community in the management and treatment of alcohol misuse in veterans.