This chapter describes in detail the theoretical and methodological fundaments that served as the basis for the research contained in this book. It starts with a detailed review of the disciplines of biological and social sciences, which, when amalgamated, can allow for a more integrated understanding of the public policy dimensions in this book. It describes how the disciplines of ecology and biological conservation interrelate with police sciences, political ecology, and environmental governance to carry out studies on the different facets of threatened species management. Other integrated concepts are the theory of change, which helps to understand the design of recovery programs, and their impact on the evaluation of initiatives. Finally, the research approaches on socio-ecological systems and transdisciplinarity are explained, which have been very useful in appreciating the interrelations between the ecological and social dimensions of threatened species management. This chapter is complemented by a detailed bibliographic review.