It has been conventional among co-management scientists to view social-ecological systems and actors and institutions found in these systems monolithically. Such a view is simplistic and conceals the complex nature of social-ecological systems and associated institutions and actors. In essence, a social-ecological system is a complex system comprised of multiple, diverse and dynamic social-ecological units, players and rules. This book entitled Co-managing complex social-ecological systems unveils the aforementioned complexity in which Lake Jipe wetland in Tanzania is the central case. This case depicts intra-, inter- and cross-scale interactions among multiple and dynamic institutions, actors and ecological systems at different dimensions of space and time. While some candidates of actors and institutions play separate roles, others play interdependent and linking roles across the multiple sectoral social-ecological units. The book introduces the layering concept of institutions and actors in three sectoral arrangements at Lake Jipe.