Gang prevention cop Jeff Norat drives a bunch of sullen teens through the gang-riddled streets of a Los Angeles neighborhood, not because they're in trouble with the law — but so they'll stay out of it.

"These kids are all at risk of joining gangs — look where they live," said Norat, motoring through Boyle Heights where some gangs are in their third generation. "But some kids don't."

What prompts some kids to join gangs and their neighbors not to join is a question that has long baffled experts. City officials, who have made little headway denting the ranks of street gangs, now think they'll find the answer through a multiple-choice test.

"If you could identify who those at-risk kids were, then you could microtarget them with resources," said Jeff Carr, director of the mayor's office on gang reduction and youth development.

That premise marks a new strategy in the city's fight against gangs, which claim roughly 40,000 members in Los Angeles, making it the nation's gang capital.

The city spends about $20 million a year on gang prevention and intervention. Until now, much of that funding has gone to what the anti-gang czar calls a "shotgun approach" to prevention — flooding gang-infested neighborhoods with social programs under the theory that any kid raised in these "hot zones" could wind up a tattooed gangbanger.

But Carr points to research showing only about 15 percent of kids in a given neighborhood join gangs, according to University of Southern California social psychologist Malcolm Klein and others. Klein found 10 factors that channel children into gangs, including poor parenting, justifying delinquent behavior and traumatic events.

Researchers at USC's Center for Research into Crime used those findings to develop the 74-question survey called the Youth Services Eligibility Test. A kid with at least five factors is deemed "at risk" and offered programs such as counseling, anger management, and tutoring.

Rather than reject a test that could stigmatize their kids, many struggling parents embrace it as a means to get their children much-needed help.

Frustrated mother Lorena Monzon was almost happy when her chronic-F daughter, Andrea, "failed" the test.

"I want something that's going to help her. Her grades are so low and her attitude is so bad," said Monzon, 29. "I'm afraid she'll get into drugs. She needs counseling."

Andrea, 12, said she likes the self-esteem enhancement programs she enrolled in. "It's pretty fun. It keeps me out of trouble," she said.

Gangs are always a risk in Boyle Heights, Monzon said. "I don't even want her to go out," she said. "There are so many gangsters around here."

On the eastern fringe of downtown LA, Boyle Heights is famed for its bright murals of Latino symbols like the Virgin of Guadalupe and pre-Columbian deity Quetzalcoatl, but it's also notorious as housing L.A.'s densest concentration of gangs.

After a gang prevention program at the Hollenbeck Police Activities League, LAPD's Norat takes the kids home. One lives a couple doors from a White Fence gang house. Two blocks later, in Evergreen turf, he drops off two brothers whose gangbanger dad was recently killed. Another boy gets out a street away from the house where a "shotcaller," or gang boss, lives.

The test found several of those kids at risk of joining a gang, but not others. Some critics say that's one problem with the test. In such a high-poverty, gang-saturated milieu, it excludes a lot of less-troubled kids who still need help. Fewer than a third of interviewed kids were identified as potential gang members.

"Any kid, if you're living in this environment surrounded by gangs, is going to be at risk," said Lorraine Garcia, Hollenbeck PAL program director.

Others suggest that kids ages 10 to 15 will tend to lie on a test that asks about drug use, parental abuse and criminal acts. Although kids are told answers are confidential, it's a lot to expect honest responses, said Jorja Leap, a gang expert at University of California, Los Angeles.

"These are kids who are afraid of arrest, afraid of being taken away from their parents," she said. "They've been schooled in not being truthful. It can take years to get their confidence."

Leap and others point to the low percentage of kids deemed at risk as a sign they're not being honest. Numbers should be higher because they were already singled out as troubled by teachers and counselors, they say.

USC's Karen Hennigan, director of the Center for Research into Crime who oversees the questionnaire scoring, said the test is a reasonable, data-supported approach and she believes kids are reasonably truthful.

Nevertheless, USC has advised case workers to build a rapport with youths by meeting with them before the interview. Agencies report that seems to be working. Hollenbeck PAL has seen the number of eligible kids triple from 15 percent to 45 percent since starting the new strategy in May.

No one knows if the test works. The city has contracted for a study in three years to see if kids the test failed to identify as gang-joiners went on to become homeboys.

"In some ways it's an experiment," Carr admitted. "But the gang problem has been endemic in LA for 25, 30 years. We have to innovate our way out of it."