The value of the multiple benefits that societies obtain from ecosystems depends (among other factors) on the health of that ecosystem which, itself, is dependent at the same time on the biotic and abiotic factors that define its structure. Furthermore, the provision of ecosystem services requires the whole ecosystem, which is not only defined by its components but mainly by the interaction of the multiple webs built within. In these webs, species can potentially influence other species, and these interactions can include both biological processes and physicochemical processes. Each species plays a different role in supporting different ecosystem services, with certain keystone species having a disproportionate impact on the stability of the ecosystem structure. The analytical framework I present in this chapter considers the network dynamics of nature, and therefore the value of species based on maintaining the balance and function of the system in order to keep providing benefits to society. There is currently a gap in the economic and finance literature with respect to the role that species play in supporting ecosystem services. This chapter aims to close this gap by presenting a five-step methodological framework to estimate the economic value of a species’ role in ecosystem service provisioning. This provides a sound justification for the investments needed to protect and restore keystone species populations and for the creation of novel financial solutions.