Health is weird. Health is weird in a way that resists simple explanations or elegant theorizing. This book is a philosophical explanation of that weirdness, and an argument that grappling with the distinctive weirdness of health can give us insight into how we might approach difficult questions about social reality. After examining extant theories of health - and finding them lacking - the book explores some particularly intractable puzzles about the nature of health, places where we often feel pulled in multiple directions or have reason to say conflicting things. On the basis of these puzzles, the book then defends a stance called ameliorative skepticism. Although health is real, there is, on this view, no way of giving a coherent, explanatorily adequate answer to the question "what is health?" Yet adopting this skeptical stance can, it is argued, help us to better understand the role that health plays in our lives, and the work that we need a theory of health to do.