This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book explores what is ecopedagogy, reinvented from various critical-based, Freirean pedagogies and research models, with the emphasis on providing the reader its tenets and defining differences from other environmental pedagogies. It discusses the needed connections between critical citizenships education and ecopedagogy, with citizenships plural to indicate the various spheres of citizenship, from local to national to global to planetary spheres. The book focuses on the use of theories within ecopedagogical teaching and research. It describes some of the local-global-planetary, anthropocentric-biocentric theoretical framings that can be utilized to understand socio-environmental issues connecting with citizenship. The book discusses the topics of development and sustainability. It offers some key needs in reinventing environmental pedagogies to become ecopedagogical, for teaching students to become global environmental citizens.