Over the years, various theoretical perspectives on agency have emerged in organizational scholarship, some of which underline the structural, systemic nature of organizations, while others emphasize the agential potentials and capacities of those who enact them. This chapter presents the main theoretical perspectives on agency in organizational scholarship, namely agency theory; neo-institutional theory; systems theory; structuration theory; critical, feminist, and postcolonial theory; and theories of hybridity, sociomaterial entanglement, and process. As mentioned, agency theorists like Mitnick examine "acting for" relationships from an institutional perspective. Institutional logics scholarship draws on work by early neo-institutional theorists such as Meyer and Rowan as well as DiMaggio and Powell, and thus focuses on how organizational structures are shaped by cognitive structures and cultural rules. Drawing on Emirbayer and Mische's influential article on agency, Poole defines agency from a systems perspective by focusing on "responsiveness and meaningfulness of an agent's actions". The chapter also presents some key concepts of this book.