Fifteen years of hard bargaining paid off last weekend as China joined the World Trade Organization. The tenacity and persistence of Chinese negotiations are proof of the importance China's leaders attach to entry into the WTO. It marks China's re-emergence as a modern nation and will fully integrate it into the global economy. It is all that and more: Joining the WTO will bring fundamental changes to China, and many of those changes will introduce unprecedented strains into the country's political, economic and social order.

In theory, China has no choice but to join the WTO. Economic modernization has proceeded apace since the country embraced reform in 1978. The results have been striking: unparalleled growth and the laying of the foundation for China's aspirations to be a regional power. Cheap labor and receptivity to foreign investment are turning China into the "factory for the world." Its growth rate has slowed slightly this year to a "mere" 7 percent, but it is still the envy of the world.

But the easy gains have been made. Continued modernization will entail more difficult and wrenching choices, and China, like any other large country, needs discipline to make them. That is the purpose of joining the WTO.