Chapter 7 offers an overview of anticommons theory, which states that when too many people own pieces of one thing, nobody can use it. Usually private ownership creates wealth. But too much ownership can have the opposite effect—it leads to wasteful underuse. This is a free-market paradox that shows up all across the global economy. If too many owners control a single resource, cooperation breaks down, wealth disappears, and everybody loses. Conceptually, underuse in an anticommons mirrors the familiar problem of overuse in a “tragedy of the commons.” The field of anticommons studies is now well established, with thousands of scholars detailing examples across the innovation frontier, including drug patenting, telecom licensing, climate change, eminent domain, oil field unitization, music and art copyright, and postsocialist transition. Addressing anticommons tragedy is a key challenge for any legal system committed to innovation and economic growth.