Several recent studies have found that charter schools, 10 years after the first was approved in California, have become more than just a promising innovation in education. On the whole, charter schools are delivering.

The $660,000 Rand Corp. study released last week was the latest among recent surveys that have reached the following conclusions: The majority of students at charter schools are performing just as well as their public-school peers on standardized English and math tests, but are doing so with a more well-rounded curriculum that includes more arts, music and foreign language classes.

Also, because charter schools are doing this with less state funding than regular public schools, they are a better value for taxpayers.

So why aren't charter schools expanding rapidly across the state?

Unfortunately, they still have one powerful opponent. Teachers' unions have long viewed charter schools as competition rather than an innovative educational alternative that empowers teachers and administrators and fosters much greater parental and community involvement.

The unions' influence on the statewide political landscape is enormous they regularly lobby school board members (some of whose campaigns they have financed) to deny charters, and succeeded earlier this summer in crushing (actually, blowing to smithereens) a proposed Assembly bill that would have championed the creation of more charter schools.

Charter schools aren't always successful. Some have struggled, and had to be shut down, usually for financial reasons. Isolated problems are to be expected. The Rand study and others have also found weaknesses in home-based charters and independent study charters, which are usually a last- resort effort to help troubled students.

Overall, though, the vast majority of charter schools are well-run, delivering on their promises, and making efficient use of public funds.

Charter schools have proved their worth and value. Now it is incumbent upon parents, communities, teachers, administrators, taxpayers, voters and lawmakers to stand up to powerful special interests and allow charter schools to flourish in California.