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On the eve of President Obama's first China visit, the state of U.S.-Sino relations remains strong. But the road ahead is uncertain and the stakes have never been greater. From the perspective of the businesses the American Chamber of Commerce in China represents—whose success in the world's fastest-growing major market is vital for the U.S. economy—Mr. Obama must make tangible progress on fighting protectionism, widening market access and addressing climate-change issues during and after his visit.

Mr. Obama has built on the positive U.S.-China momentum that President Bush developed later in his presidency. By focusing significant energy on areas of common ground, like cooperation on climate change and stimulus spending, while downplaying third-rail...