In the previous chapters, we focused on particular aspects of this book’s overarching theme, namely, the economic valuation of biodiversity. In Chapter 2 the focus was on economic valuation: its theoretical foundations and its conceptual reach. Chapter 3 took a closer look at the concept of biodiversity: its definition, approaches to measurement and its ‘ecological value’. In the environmental ethics excursus we then looked at issues of biodiversity value from a more abstract, philosophical perspective. Before we will be able to combine these insights, which will culminate in a conceptual framework for the economic valuation of biodiversity (Chapter 5), in this chapter we review the state of the art of the economics literature on biodiversity value. This review has two parts – its first part focuses on the empirics of economic valuation and presents a comprehensive critical review of existing biodiversity valuation studies; the second part presents selected conceptual arguments about the sources and nature of the economic value of biodiversity. This rather unusual and somewhat counterintuitive order is dictated both by the fact that the author started working on the subject by looking at the empirical literature and by the relative detachment of the latter and the conceptual perspectives. This detachment means that, given the conceptual focus of the present book, the theoretical and conceptual literature can be viewed as refining the ‘raw’ insights provided by empirical valuation studies.