This thesis develops a methodology to capture ‘social value' in a national-level index. Social value describes the individual and collective benefits derived from social, economic and environmental goods and services. Gross Domestic Product (GDP) is often treated as a proxy measure for social value (at least implicitly), and large parts of policy are geared towards increasing it despite significant conceptual and methodological flaws. Alternatives to GDP, including subjective well-being are reviewed but none are found to provide an adequate framework for setting collective goals and driving policy decisions to achieve those goals. A conceptual framework – constrained utilitarianism – is developed. This is a hybrid of the most appealing features of modern theories of value: objective list theory, hedonic theory and desire theory. The framework combines people's subjective preferences with ‘expert' opinion on phenomena such as climate change, which people may not prioritise. The framework is then applied to the Republic of Ireland. Subjective views of the things people value are canvassed through an online survey of people resident in Ireland. Ten outcome areas emerged from the research and appropriate national indicators were identified. Due to the data limitations that individual researchers inevitably face, the approach is not fully operationalised as an index, but illustrated through a comparison with GDP in a dashboard format. The full methodology, however, is designed to be used by national policymakers who would have, or could obtain, the data required to operationalise the approach. I highlight three key innovations. First, the conceptual framework provides a structure for collectively agreeing goals, whilst constraining those choices subject to (for example) scientific evidence. Second, I challenge the requirement for such indices to be internationally comparable and make the case for more culturally-specific measures of social value. Finally, I argue that a test of such an index is its relevance for policy i.e. that it identifies changes that can improve the lives of citizens in a way that is transparent and increases the accountability of policy-makers. I show through two worked examples – mental health and the environment – how such an approach would lead to different directions for policy. Several areas of future research are identified, including issues with collation, ownership and use of data in the public sphere.