In California last month, a chain of 60 charter schools closed abruptly because of financial problems and mismanagement, stranding more than 6,000 students three weeks before the start of classes.
But in New Haven, Conn., one charter school is so successful that its students are out-scoring peers in nearby wealthy, white suburbs and its founders are being recruited to operate schools in New York City.
More than a decade after Minnesota educators opened the country's first charter school, the national debate over their value rages as fiercely as ever.
Now Maryland is poised to approve its first batch, giving families across the state a new kind of school choice.
In Baltimore, which loses hundreds of families each year as their children reach school age, desperate middle-class parents hope charter schools might give them a way to stay.
Publicly financed but independent of local school systems, charter schools are frequently smaller and more responsive to parent concerns, with a freedom to innovate.
A study of national test scores by a teachers union this summer suggests charter school students score lower than students in regular public schools. But advocates argue that in some of the country's most impoverished inner cities, charter schools have found remarkable success helping minority and poor students achieve at levels far higher than nearby neighborhood public schools.
Harvard University's Paul Peterson says that whether charter schools have succeeded or failed, "they have introduced a lot of experimentation into American education" at a time when many urban school systems are struggling.
"I think whatever anyone says about charter schools is true," says Peterson, director of Harvard's Program on Education Policy and Governance.
Charters have become a cause of conservatives who champion more accountability and testing in public education and push for charters as part of their broader support for privatization and vouchers.
On the other side, teachers unions and some other public school advocates believe these schools might skim off the most involved parents, taking away money and attention.
But in urban areas with troubled schools, the charter movement unites people who support the notion of public education yet are frustrated that big city districts are slow to change. Groups of parents, teachers and community activists have banded together to start charters, though several for-profit companies have jumped into the market, too.
About 2,900 charter schools are operating across the country, concentrated in Michigan, Arizona, California, Florida and Texas - states where laws were written to encourage their proliferation.
Maryland legislators came late to charter schools and have chosen a more cautious approach, crafting a law in 2003 that puts local school boards in charge of deciding who gets charters and makes them responsible for overseeing the schools once they're running.
The law gets a poor rating from the Center for Education Reform, a charter advocacy group, which believes it will severely limit the number of charters. "The Maryland law is virtually not a charter law," says its president, Jeanne Allen.
There's only one charter in Maryland so far - a Montessori-themed one opened two years ago in Frederick County. The closest thing to charters in the city has been Baltimore's experiment over the past seven years with more than a dozen charter-like schools, including the highly successful Midtown Academy in Bolton Hill, and others with more uneven records such as New Song Academy in Sandtown Winchester.
Charters are often elementary schools with an average of 269 students. Prohibited from charging tuition, they receive per-pupil allotments from local school budgets. When applications exceed available spots, students are picked by lottery.
Within three years, state Superintendent Nancy S. Grasmick says she hopes to see about 20 new charters open across Maryland. In Baltimore, 10 groups have filed applications to open new schools and others have asked to convert seven existing schools to charters.
`Serving our children'
"My hope for charter schools in Maryland is we understand that these are public schools that are serving our children," Grasmick said. "We will have some charter schools that will provide an outstanding learning environment for children."
Such was the case in New Haven, Conn., six years ago, when a group of Yale University law students spearheaded the opening of a charter school to attack the gap in achievement between poor, minority children and the white middle class.
Amistad Academy's eighth-graders - overwhelmingly poor and minority - are now outperforming their peers in New Haven and in wealthy suburbs around the state.
Amistad has been so successful that New York City Chancellor Joel I. Klein asked the school's officials to apply to open five charter schools in his system in the next two years.