Book excerpt: Many people think prisons are all the same-rows of cells filled with violent men who officials rule with an iron fist. Yet, life behind bars varies in incredible ways. In some facilities, prison officials govern with care and attention to prisoners' needs. In others, officials have remarkably little influence on the everyday life of prisoners, sometimes not even providing necessities like food and clean water. Why does prison social order around the world look so remarkably different? In The Puzzle of Prison Order, David Skarbek develops a theory of why prisons and prison life vary so much. He finds that how they're governed-sometimes by the state, and sometimes by the prisoners-matters the most. He investigates life in a wide array of prisons-in Brazil, Bolivia, Norway, a prisoner of war camp, England and Wales, women's prisons in California, and a gay and transgender housing unit in the Los Angeles County Jail-to understand the hierarchy of life on the inside. Drawing on economics and a vast empirical literature on legal systems, Skarbek offers a framework to not only understand why life on the inside varies in such fascinating and novel ways, but also how social order evolves and takes root behind bars.