​This book provides an account of what is to know what things are, focusing on kinds, both natural (such as water) and social (such as marriage). It brings tools from an area that has received much attention in recent years, the epistemology of inquiry. The knowledge of what things are is to be understood as resulting from successful inquiries directed at questions of the form ‘What is x?’, where x stands for a given kind of thing. The book also addresses knowledge-wh in general (which includes knowledge-who and knowledge-where), as well as the phenomenon of ignorance regarding what things are and our obligations in respect to knowing what things are. It also brings to light new avenues of research for those interested in the relation between the knowledge of what things are and concept possession and amelioration. ‘Knowing What Things Are’ should be of interest to researchers in Epistemology, Philosophy of Language,Metaphysics, Philosophy of Mind, Social Philosophy and Linguistics.