Understanding the contributions from the environment to society is seen as increasingly important globally. In Scotland this is currently a high priority, as policymakers begin to shift attention away from traditional wellbeing indicators such as GDP. Although alternative natural capital accounting techniques exist, and are useful for creating commeasurable market values, they are unable to account for the full suite of benefits derived from the environment. Scotland's Natural Capital Asset Index (NCAI) is an attempt to create an account of Scotland's natural capital stock and how it's potential to contribute to wellbeing changes on an annual basis. This paper describes the inputs, calculation process and results of the NCAI. It also reports on sensitivity testing of the model, which found the model to be robust, credible to policy makers and meaningful, thus achieving the overall aims of the indicator.