Gambling, prostitution, drugs, arms trading, oil smuggling, and trafficking in people—these six illegal businesses are large and getting larger in Thailand. They distort the economy and victimize people. They are increasingly linked together through networks of protection and organized crime. They help to fund Thailand’s corrosive “money politics” and to sustain corruption in the police. The authors argue that control of the illegal economy, especially through reform of the police, is vital for the development of a modern economy and functioning democracy.