The thesis presents an integration of Sen’s capability approach as a welfare assessment framework with the domain of the natural environment. The purpose of this is to develop a conceptual framework for analysing and empirically measuring people’s ability to exercise choice over valuable welfare outcomes (their ‘beings’ and ‘doings’) with respect to the environment. In this way, Sen’s capability approach offers an alternative approach to evaluating environmental value based on the metric of freedom, expressed in terms of the metrics of capabilities and functionings.