HALTOM CITY, Texas -- Diane DeSoto is a typical PTA mom: eager to help and plugged in to her children's lives. But when her daughter's kindergarten teacher asked if she would lend a hand with school activities, she had to make an embarrassing confession.

"I'd love to, but I can't," Ms. DeSoto said. "I wouldn't pass the background check."

Ms. DeSoto, 41 years old, was convicted of felony amphetamine possession in 1992, which disqualifies her from volunteering in her suburban school district near Fort Worth and in a growing number of other places around the country. Sept. 11, the Catholic priest-molestation scandal and a series of lurid child kidnappings are combining to stoke parents' anxiety as the new school year gears up. And that's prompting more and more districts to require parents to undergo criminal-background checks before being allowed to accompany their children on field trips or help out with holiday parties.

Criminal convictions, and sometimes merely an arrest, can lead to a ban on volunteering. Parents who refuse to provide their Social Security or driver's license number can also be barred.

Supporters of the policies, including many parents, see the checks as another way to protect children's safety. But opponents worry about branding parents unfit even after they have paid their legal penalty for crimes or when their offenses -- such as bouncing checks or shoplifting -- don't suggest a threat to student safety. "Once we start down the path of morally judging who can and cannot go into their child's classroom, we are treading on dangerous ground," says Barbara Clark, president of Nevada's Parent Teacher Association. She has helped fend off a proposed law in that state that would require background checks.

Ms. DeSoto doesn't make any excuses. "I was a drug addict," she says. In 1992, she was sentenced to probation, which she violated in early 1996 by again using amphetamines. That landed her in prison for more than three years.

After her release in April 2000, she set about trying to repair the damage she had done to her two daughters, now 13 and 7. She says she has been drug-free since 1996. She works selling wooden playground sets and is active in a local church dedicated to helping families of former inmates. She hopes that by turning around her life, she can steer her children away from the mistakes she made.

But she is saddened and frustrated that she can't participate more in her children's school activities. "I want to be that mom in my child's life," she says, especially when her younger daughter pleads with her to go on the class field trip like the other moms. "It's just really devastating," says Ms. DeSoto, who now uses a different married name but asks that it not be printed. "I know I have a past, but you have to understand, some people do change."

Increasingly, schools aren't willing to take that chance. Ronald Stephens, executive director of the National School Safety Center, estimates about half of the nation's 15,500 public-school districts have background checks for volunteers. The center provides safety training to teachers and administrators.

As the volunteer coordinator for Charlotte-Mecklenburg schools in North Carolina, Patricia Robson has screened 17,000 volunteers since the district began checking backgrounds in January 2001. Parents who are flagged must come in and explain the circumstances of every arrest, charge or conviction, providing documentation on how it was resolved. "I have people in my office crying," says Ms. Robson. "It's something that happened in their life a while ago. They're very sorry that it happened, and they've made restitution."

Her district is mainly looking for felonies like assaults, sex crimes or child abuse. But more than 100 parents were asked in the first six months to explain bounced checks, which show up as fraud, Ms. Robson says. Many shoplifting cases have also surfaced. One parent had the awkward task of explaining an arrest stemming from a soured extramarital affair, although the charges had been dropped. That parent was allowed to volunteer. Ms. Robson has formally turned down only about a dozen people as volunteers, but she says several hundred dropped their volunteer pursuits after getting her call reporting that a check had turned up a problem.

Background checks have been common for years for teachers. Private youth groups such as the Girl Scouts and Boy Scouts also screen volunteers. Now schools are requiring would-be volunteers to fill out forms describing their backgrounds. The schools typically then send the paperwork to state police, who check for any criminal history. In addition to identifying potential dangers, this routine demonstrates a school district's concern for safety and may help it fend off possible lawsuits if students are harmed by a wayward volunteer, educators say.

In January, the Houston Independent School District, which serves 200,000 children, began screening its volunteers. "You must act to over-prevent -- even at the cost of the relationship between parents and the school district," says Cathy Mincberg, the district's chief business officer.

Michelle Alabaster, a Broward County, Fla., mother of two children, had been a school volunteer since 1989. She had helped in the school office, mentored students and won a Volunteer of the Year award in 1999.

But a background check in 2000 uncovered a weapons offense. During a 1995 visit to her dying brother in Texas, who was talking about suicide, Ms. Alabaster says she found two handguns in his apartment. She decided she should take them away. She says she packed the weapons in her suitcase, intending to give them to a police-officer friend. Following her airline's guidance on the legal way to transport the weapons, she checked the bag containing the guns. But because she was running late, she says, an airline employee gave the bag back and told her to check it at the gate. The gun was discovered at an airport-security checkpoint, and she was arrested.

She pleaded no contest in 1995 to unlawfully carrying a weapon in an airport. She received "deferred adjudication," meaning the conviction wouldn't be recorded if she served her probation without incident, which she has done, according to court records.

Ms. Alabaster says she provided all of the documentation school officials asked for, but they still banned her. When she got the news, she says, "I burst into tears. I was devastated. I had devoted my life to these children. I thought I was making a difference."

Weapons charges are especially sensitive for schools, explains Bill Tegtman, a Broward school official who participated in the Alabaster review. "Deferred adjudication does not make it go away like it never happened. We've heard as many stories as you can imagine."

The process can be traumatic even when parents are ultimately cleared to volunteer. When Coos Bay, Ore., elementary school principal David Laird called a parent to talk about a misdemeanor conviction, "it was like I dropped a bombshell," he says. The principal checked references and decided to let the parent volunteer. Although he sees the checks as a necessary safeguard, Mr. Laird says, "if we all got caught for what we did when we were younger, we'd all have criminal records."

At a time when numerous studies stress the importance of parental involvement in schools, opponents of background checks worry they will scare parents away. One lapse in judgment "doesn't mean they haven't turned out to be good, dedicated parents," says Donna Riani, who helped reverse a background-check policy in her suburban Chicago school district during her tenure on the school board in the mid-1990s.

Enforcing background checks can be especially hard on urban schools with low-income, minority populations, says James Hammonds, who served as a parent representative on his local Chicago school-advisory council until his term expired this summer. A father of four, Mr. Hammonds, who is African-American, says his volunteer efforts focused on getting other minority parents involved in the schools. That's a tough task with inner-city parents, many of whom are struggling economically and lack role models of involved parenting. Background checks and the prospect of government prying into their lives give some minority parents "one more reason not to get involved," he says.

Privacy concerns are stopping some parents from volunteering. Angie Choiniere, a past PTA president in Charlotte, N.C., was barred from chaperoning students overnight when she refused to provide her Social Security number for a background check. Ms. Choiniere says she worried about who would get access to information she gave to school officials. Earlier, she had been a victim of "identity theft" when her credit-card information was stolen at a restaurant, she says. The thief was able to obtain her Social Security number and order new credit cards in her name.

Some skeptics point out that checks don't always protect children, since many child molesters don't have criminal records. In June, Andy J. Sconzo of San Antonio, Texas, was sentenced to 10 years in prison after pleading guilty to indecency with a child for fondling young school friends of his daughter. Before his arrest in February 2001, Mr. Sconzo had passed a background check administered by the San Antonio schools. He had also coached swimming and soccer in the area and was a youth leader at his church.

The screening "did not help us, unfortunately," says Steve Henry, a school-district spokesman. Since Mr. Sconzo's arrest, the district has tightened its screening rules, barring any volunteers who have anything questionable on their record. For example, any drug offense, no matter how old, and "you're out," says Mr. Henry.

Deborah Nicholas of Dallas says she has worked hard to get her life in order after she was convicted of murdering her husband in 1980, when she was 23. He was abusive, drunk, and threatening her with a gun, she says. "I grabbed the gun as he was reaching for me," she says. She was paroled after 5 1/2 years in prison and remarried.

Times were rocky for a while, but she says she straightened out her life, became deeply involved in church and now ministers to current and former prison inmates through a volunteer program. She also has an eight-year-old son.

Fortunately, says Ms. Nicholas, her job as a real-estate agent allows her to pay for a private church-based school that allows her to be fully involved as a volunteer and field-trip driver. "Most people there know me and know all about me," she says.

Ms. Nicholas says she understands a school's hesitation to allow parents with criminal records around other kids. But for her own son, she says, "it's very, very important for him to know that I'm there. I'm trying to give him a different life."

Write to Susan Warren at susan.warren@wsj.com ²