First, political leadership is crucial. "President Bush has provided good leadership," says Mettimano, "both on human trafficking and sex tourism." He increased spending on programs to fight the trade; issued an executive order requiring departments to confront the issue; and, in his 2003 address to the U.N. General Assembly, shamed nations that tolerate child prostitution. In any eventual assessment of Bush's foreign policy idealism, his personal engagement on issues such as HIV-AIDS, human trafficking and child sex tourism will need to be taken into account.

Second, legal changes can matter greatly. Before congressional passage of the Protect Act of 2003, prosecutors had to prove that sex tourists went abroad with the intent of molesting children -- something almost impossible to demonstrate. The Protect Act shifted the burden, making predators liable for the act itself. Penalties were doubled from 15 years in prison to 30. And with convictions more likely, law enforcement officials and prosecutors have been more motivated.

Third, religious activism makes a difference on a global scale. For several years conservative Christians have been at the forefront of the campaign against modern slavery, working closely with traditionally liberal human rights groups. Support for human trafficking legislation in 2000 included the unlikely pair of Chuck Colson and Gloria Steinem. This kind of alliance is potent because it communicates a broad national commitment.

These efforts are not unprecedented, and neither is the issue of child prostitution. A House of Lords report in Victorian England found that "juvenile prostitution from an almost incredibly early age is increasing to an appalling extent." In 1885, a crusading editor of the Pall Mall Gazette set out to demonstrate that children could be readily bought and sold in London. He managed to purchase a 13-year-old girl named Elizabeth Armstrong from her mother for 3 pounds sterling on delivery and 2 pounds more when her virginity was confirmed.

The story about Armstrong -- headlined "The maiden tribute of modern Babylon" -- sold a million newspapers in a week and ignited a national scandal. The Salvation Army opened houses of refuge for prostitutes and sent out Midnight Rescue Brigades to counsel young streetwalkers. And the British Parliament quickly increased the age of consent from 13 to 16.

Yet it remains possible in our world to purchase 13-year-olds. Some Americans do it all the time. And it still deserves our outrage and activism.