This book explores the notion of organismal agency from the perspective of both philosophy and biology. The two sections of the book delve into parallel themes, including distinctions between organic and inorganic nature, self-organization, autonomy, self-presentation, memory, umwelt, and environmental influence. The philosophical part focuses on the influential thinkers who shaped our perception of living entities beyond mere mechanisms. It scrutinizes the concepts of organism and nature in the works of Aristotle, Kant, Schelling, and various processualists. Each chapter explores facets of their ideas that directly or indirectly foreshadowed or contributed to the formulation of the concept of agency. The biological part of the book investigates various concepts associated with agency such as experience, meaning attribution, and phenotypic plasticity, as well as reproduction, organisational constraints, modularity, development of integrated phenotypes, organismal choices, or self-representation through animal organisation. In essence, this work offers a comprehensive examination of organismal agency and its philosophical and biological foundations. Collaboratively authored by individuals from several institutions, this publication caters primarily to researchers and students working at the intersection of philosophy and biology.