YINGSHANG, China -- In a sparsely furnished farmhouse, about a half mile from a main road in the poor, rural province of Anhui, 16-year-old Zhao Yan has lived on her own for more than two years.

She goes to school, tends to the family rice farm and waits for her father's periodic visits home. "I miss my dad a lot," says the teen, dressed in jeans and a lime-colored hooded sweatshirt.

Chinese authorities estimate that 22 million youngsters in China have been left at home while their parents migrate to cities to find work. The numbers of the so-called liushou ertong, or "left behind children," are growing steadily in China's vast rural areas. They represent a personal toll of China's explosive growth.

As China's economy booms, some 200 million farmers are moving to cities to pursue opportunities. China's laws make it almost impossible for migrants to school and care for their children where they find work. With little money, many simply leave them behind and hope for the best.

Zhao Yan's father, Zhao Changliang, a farmer, left his land and only daughter two years ago. His wife died when Zhao Yan was a little girl. When she was old enough to cook for herself, he paid 200 yuan, or about $25, for a ride with neighbors to Shanghai, joining more than 8 million migrants who have left Anhui to find work in China's urban centers.

Many of the left-behind children stay with one parent. But over 30 percent of the children of migrants are left with grandparents or with other relatives with little or no supervision, according to a 2004 survey by the China National Institute for Educational Research.

The problem is tearing apart families and creating a generation of children who grow up with limited contact with their parents and little adult supervision. Teachers in provinces such as Anhui say it is common to visit or call a student's home only to find there is no adult in charge.

In one Anhui compound where a cluster of families have created a small community, an elderly man and his wife are the guardians of five children under the age of 6, whose parents work year-round in Shanghai.

"Most of the children are still too young to know the difference, but the oldest one cries every New Year when they leave," he says, pointing to his granddaughter. "There's no choice in the matter. This is the way things are these days."

Wu Peigen, a 14-year-old middle-school student in the same county, says his father left to find work when he was in first grade. After working several years in a neighboring province, his father's health began to deteriorate. Last July, Peigen's mother went to care for him. Peigen now lives with his grandparents.

"I didn't totally understand at the time. I was just sad," says Peigen, who especially misses his mother on weekends. He says his parents "told me to listen to my grandparents. My mom was sad and she cried. I don't know when I'll see her again." His parents call about twice a month to ask him how he's doing in school.

On most days, Zhao Yan wakes early, then takes a 30-minute bicycle ride to school. She returns to an empty home to cook for herself. Her dogs run out to the road at the sound of her voice when she gets close to her small brick house. They sit by her as she begins her daily ritual of lighting a fire in the large brick oven she uses to cook.

An elderly woman who lives next door occasionally visits, and sometimes Zhao Yan has friends over. But the dogs and a borrowed black-and-white television are often her only companions. The middle-school student does her homework by the glow of the screen and listens to music videos in the unheated house.

"There isn't much to do when my father isn't here," she says.

Even though she enjoys her literature class and thinks it would be fun to be a teacher, she has difficulty keeping up with school. Several days a semester, she has to skip classes to work on the family farm. Going to high school isn't likely; it would cost at least hundreds of dollars a year, which is more than her father can afford.

Zhao Yan's father leaves about $100 for her each time he goes to the city, usually for two to three months at a time. She uses the money to buy groceries -- mostly vegetables, because she waits for her father to return to eat meat, which is more expensive. Without her father around, Zhao Yan says she sometimes skips meals. She prefers to cook for him during the Lunar New Year and harvest seasons when he returns home for a few weeks.

As China's cities continue to develop, the government expects the migrant-worker population -- and the numbers of left-behind children -- will rise. The State Council Research Office reported in April that the 200 million people in nation's rural migrant-labor force make an average of about $60 to $100 a month. Many of these workers were just getting by on subsistence farming before leaving.

Ye Jingzhong, vice dean of the school of Humanities and Development in Beijing's University of Agriculture, says that when children are left behind it can lead to behavior problems and mediocre performance at school. He blames the situation on China's hukou system, where farmers who move to China's cities to work are placed under separate educational and housing regulations -- meaning they can't apply for public housing and their children have to pay higher fees to go to city schools. Though the government has said it aims to ease the rules, revisions made to the system in Beijing and Shanghai apply mostly to white-collar workers.

Chinese authorities created a coalition of government agencies and nonprofit organizations in October to propose programs that can help migrant families. No recommendations have been made yet.

Since her only relatives live about 10 miles away, Zhao Yan's friends are her greatest support network. They ride to and from school together and spend some weekends playing badminton or watching TV. When she needs help, they often offer -- even when she had to fertilize a huge plot of land all by herself.

Mr. Zhao works construction jobs and doesn't carry a cellphone, so his daughter has to wait for him to call her neighbor's house every few weeks. In emergencies, she borrows money from neighbors and gets medicine for herself when she's sick.

During a trip home in November to help Zhao Yan with the harvest, Mr. Zhao's skin was dark from working outdoors all day, and he looked older than his 50-odd years. He says he hopes that by working in the city, he will earn enough to improve the family's living conditions. He has three children: one son in the military, one son working as a mechanic in Shanghai and Zhao Yan.

"We need to renovate our house," he said. "One day soon, my son will come home and we'll all need to fit in this house."