Dirty theory follows the dirt of material and conceptual relations from the midst of complex milieus. It messes with mixed disciplines, showing up in ethnography, in geography, in philosophy, and discovering a suitable habitat in architecture, design and the creative arts. Dirty theory disrupts a comfortable status quo, including our everyday modes of inhabitation and our habits of thinking. This small book argues that we must work with the dirt to develop an ethics of care and maintenance for our precarious environment-worlds.