Why is productivity higher in cities? Does urbanization cause growth or does growth cause urbanization? Do countries achieve rapid growth or high incomes without urbanization? How can policy makers reap the benefits of urbanization without paying too high a cost? Does supporting urbanization imply neglecting rural areas? Why do so few governments welcome urbanization? What should governments do to improve housing conditions in cities as they urbanize? Are innovations in housing finance a blessing or a curse for developing countries? How will governments finance the trillions