This book examines how environments and organisms dynamically produce one another. As such, it takes its title very seriously (and very literally): to speak of environment plus organism is the only viable way where neither term gets to be reduced to the other. It is rather their coming together, what thinkers like Gilbert Simondon call transindividuation , and it's unfolding that stand as the most exigent ambition of this book. In simple terms, this book claims that the minimum unit of analysis in any architectural account is always the environment, the organism and their (technological) plusing , examined as one. The book has three interrelated ambitions, which are fundamentally pedagogical: 1) Irreducibility : it 'makes no sense whatsoever to try to understand the anatomy of half a chicken' as Gregory Bateson puts it, and this book makes a constant plea for an architectural account of the Batesonian claim. 2) A Real Copernican Revolution : our engrained anthropocentrism always sees the organism as antecedent to the environment. To counter it, this book cultivates an architectural ethos that sees organisms and environments as co-constitutive equals. 3) Exteriority of Relations : highlighting the power of plusing , this book underscores the ever-changing how of a form of life. A mode of existence never pre-exists an event of plusing environments and organisms. Readers of this book will be exposed to an original philosophy of architecture that brings together transdisciplinary concerns through concrete architectural examples, while opening its audience to a broad population of interests, from social sciences to media studies and affect theory. Written in a playful manner, it wishes to make accessible notions, concepts and ideas that can transform contemporary architectural thinking and open it to a broad speculative logic. This book will be of interest to researchers and students of architecture, architectural theory, architectural history, and philosophy.