"Parents think they're the only ones going through it. It's horrible," Wagner said.
"It's heartbreaking, and it tears families apart."
Last month, Wagner and fellow officer John Alaniz convened a group of such parents for the launch of a strictly confidential class on how to handle strong-willed teens.
Two rooms full of parents one English-speaking, one Spanish-speaking gathered on a weeknight at Greendell School.
For three hours with no break fueled by Subway sandwiches, candy and Peet's coffee the parents bonded over stories about their kids, according to a mother who was present.
The mother's child a popular Palo Alto High School student has had multiple contacts with police, including a citation for possession of marijuana.
"Traditional parenting can be effective with compliant kids, but with strong-willed kids traditional parenting isn't effective so you need ways to be effective without shutting them down," she said.
The 12 parents in the English-speaking room interviewed one another and then introduced their interview partners to the larger group.
"It was completely open you could share things if you want to, but you didn't have to," the mother said. Parents pledged to maintain confidentiality about discussions of particular children and the identities of other parents.
They received a homework assignment to report back the next week on how their teens reacted when the parents "showed them love in a tangible way every day" through notes, hugs or verbal expressions.
"It sounded pretty obvious to me, but there was someone in the class who said, 'I don't want to tell my kids I love you,'" the mother said.
"There are definitely kids out there who aren't getting that regular dose of verbal or physical love from their parents."
The Parent Project class is now in the fourth week of a 12-week series. A joint project of the police department and the Palo Alto Adult School, it has been offered twice a year in Palo Alto for the past five years.
Parents are referred to the class either by the school district, the police or, occasionally, by a juvenile-probation officer. Police said they typically reach out to parents of teens who have had multiple, serious contacts with the department.
"I send a letter not to every, but close to every, family whose child has been arrested more than once in that year," Wagner said.
"For example, if a child has no discipline history with the school district and shoplifted a soda at Long's, I'm not going to send a letter. But if a child has a discipline history at school and was cited for smoking weed at 11 p.m. out on a corner, it's a case where, if the parents made a bigger effort, everyone could benefit."
The Paly mother received her invitation from Police Department School Resource Officer Nanelle Newbom.
After recounting police contacts involving the woman's child, Newbom's letter said: "I'm not writing to you as an officer but as another parent of teenagers. Most of what I'm talking about here is not a matter for police to address, beyond safety concerns.
"It is for you to handle as a family."
Newbom said she sent 42 personal letters to solicit enrollment for the current class and circulated 400 fliers.
The Paly mother had already initiated an informal support group of parents of her child's friends.
"Palo Alto is in denial about these things," she said.
"We have this image to uphold."
The mother said she was pleased the first session had focused on the importance of parents expressing unconditional love for their children.
"Instead of making you feel like you're doing something wrong, they focus on the fact that while we cannot control our kids, we can manage them in a different way," she said.
"We talked a lot about short-term consequences, taking away things they enjoy for a short period of time."
Police officers, all too familiar with middle-of-the-night youth busts, said the Parent Project is one of the most effective tools in their arsenal to improve out-of-control teen behavior.
Calls for police to respond to the households of parents who have taken the class are eliminated or sharply reduced, Newbom said. Those parents who still call the police, she said, "tended to be the ones who were inconsistent in their attendance and participation."
Beyond coaching on steps toward "active, engaged parenting," a key goal of the course is to foster longer-term bonds among parents.
"Many parents comment that what they like most is being able to talk to other parents who have the same problems," Newbom said.
"They feel alone because their next-door neighbors who can hear all their family arguments appear to have perfect children who are attending school and on their way to Harvard."
In addition to the 12 parents in the English section, 14 are enrolled in the Spanish section.
Forty-two couples had been invited.
"I think there's a time commitment issue and maybe a feeling of, 'Oh, I don't need that,'" Wagner said. "It may be hard to admit that you need some skills."
The Parent Project is a "high-commitment class," she said. Consistent participation is critical because the curriculum builds from week to week.
"The parents want all the answers the first night they just want to go home and read the book. But you can't just read the book. It's about the facilitation, the other learning tools, the parents interacting that's what you get from it, as well as the support group."
Kara Rosenberg, principal of Palo Alto Adult School, a class co-sponsor, said she audited the first series of The Parent Project and was initially skeptical.
"I think the parents felt the same way. ... But what I saw at the end was that the parents were confident. Not all their problems were solved, but they had strategies to help them.
"And it's nice for the parents to have these connections with the police department outside of their kids being in trouble.
"It may be trite to say, 'It takes a village,' but that is to some extent what this does. It helps parents create a network to help each other out and to know they're not in it alone."