The participation of individuals with disabilities in society often relies on social services and support. Yet, due to resource scarcity, governments must carefully assess the effectiveness and cost-efficiency of these services. Evaluating interventions can be challenging as their outcomes extend beyond just health and often impact various government sectors. This thesis enhances disability service evaluation by analysing evidence, identifying gaps, and introducing a tool to calculate utility scores. It explores the impact of the Australian National Disability Insurance Scheme on participants, their carers and the broader disability population, which carries strong economic and policy implications.