Beijing ? With all the media focus on “Rising China,” another side of China gets far less attention. Call it “the other China,” the bulk of the country’s population that hasn’t fully shared in the astonishing economic boom of the last 30 years that has transformed the country.

I’ll be looking at “the other China” as part of a two-week Gatekeepers Editors’ Trip to China sponsored by the International Reporting Project at the Johns Hopkins University School of Advanced International Studies. We’ll be traveling to rural areas in Sichuan and Yunnan Provinces. We’ll be looking at China’s urban-rural divide, at the pressing environmental and health issues the country faces. We’ll also be examining the economic challenges China must confront if it is to close its rising gap between rich and poor — and maintain stability at home.

China’s level of development matters to the rest of the world for many reasons. For example, a China still focused primarily on domestic development is less likely to pursue adventures abroad (although its search for resources to fuel its growth has led to a much more active foreign policy). And a China that considers itself part of the developing world will be less willing to commit to the emissions targets sought by industrialized nations to combat global warming.

Yet, China’s growth spurt is so constant, its evolution so dynamic, that its global economic status is difficult to define.

Ten years ago, the prominent Chinese economist Hu Angang coined the phrase One China, Four Worlds. China’s First World, says Sinologist Anne Thurston, includes its biggest cities, Beijing, Tianjin, and Shanghai. Its Second World is made up of the less affluent but still fairly prosperous belt along its eastern coast.

The population of these two worlds amounts to about 300 million out of 1.3 billion Chinese, she says. But the bulk of China’s population, she points out, lives in its Third World, a larger belt running north to south inland from the coastal areas. The country’s Fourth (and poorest) World includes its impoverished provinces in the West, where average income is below $3 a day.

“Just as China is growing faster than any country, its rate of inequality is also growing faster,” says Thurston. That inequality, she says, takes several forms: urban vs. rural, East (prosperous) China vs. West, and the inequality within large cities, created by the massive migration of rural poor to urban areas in search of work.

Visiting Beijing for the first time in five years it is certainly possible to imagine that one is in the First World.

Post-Olympics, China’s capital sports endless new rows of glass skyscrapers, some with strange shapes, or curving roofs, and a massive, glitzy new airport terminal. High-end shopping malls line the major boulevards, and traffic jams outpace the highways expanding ever outward in concentric circles.

Students at elite Tsinghua University have the sophistication of their counterparts at Harvard or MIT. They dress in T-shirts and jeans, many speak English and have traveled abroad, and most blog. They hop on bicycles to wheel around a large leafy campus that has a familiar college feel. (These students live far more prosperous lives than did their parents: one doctoral candidate in oceanography told me she and her parents shared two small rooms with another family when she was a small child; the family was finally able to move to a two-bedroom apartment when she was 16. I heard similar stories from many other young Chinese.)

Young working people in a high-rise office complex duck into Starbucks for a latte, and troop down to a basement mall to pick up lunch fixings at a supermarket. At night, the restaurants around QianHai Lake are filled with young people out on dates or in groups, and Chinese joggers in sweatpants swing by women walking their dogs. The whole scene is illuminated by shimmering lanterns hung from posts around the water’s edge.

But these snapshots reflect only a tiny slice of a country whose economy is in constant flux.

China’s politicians and academics argue among themselves about where China stands on the economic ladder. On a visit to Hu Angang, at Tsinghua’s school of Public Policy and Management, he insisted his famous phrase was obsolete. “My slogan of One China, Four Worlds was for 10 years ago.” Using new analytic tools, he now insists that China mainly belongs to the First and Second Worlds, with only Tibet still languishing in Third World status. In his estimate, China’s Fourth World has now disappeared.

On the other hand, Xie Zhenhua, vice chairman of China’s National Development and Reform Commission and a key negotiator in climate-change talks at Copenhagen, Denmark, told us that “China is still a developing country …

“Development in Beijing and Shanghai does not represent all development in China,” Xie insisted. He said that when House Speaker Nancy Pelosi traveled by high-speed rail on a visit to China last year, “she thought it showed that China was not a developing country. But there are still great disparities between rural and urban communities and between East and West China, so I hope you can perceive China with an overall view.”

That’s what I’ll be trying to do in the coming two weeks.

— Trudy Rubin is a columnist and editorial board member for the Philadelphia Inquirer. trubin@phillynews.com