"If that would have happened, zero tolerance, I would think, I would get sent ... home, get everything taken away from me," said Alex Whirledge of Anaheim, Calif., who was an eighth-grade bully. "It would have stopped."
Alisha Mendez, now a high school senior in Middletown, Pa., said her thirst for attention, which turned her into a middle school bully, would have been quenched faster if her school had had a tough anti-bullying policy and enforced it.
"It would have -- 180, right around," Mendez told "20/20" co-anchor Chris Cuomo.
To date, 45 states have passed laws requiring a range of anti-bullying actions, from implementing prevention programs to reporting incidents to the police. But child behavioral experts say few schools have zero-tolerance policies in place.
"The school needs to be clear about what the ramifications will be for bullying, which most schools are not," said Dr. Gail Saltz, a psychiatrist and author of books about adolescents' thinking.
"There's going to be a price to pay. It's going to be suspension, it's going to be detention, it's going to be something that not only you don't want but your parent [too]."
What drives someone to become a bully in the first place?
"I was a bully because I was being bullied," said Whirledge, now 14 and a high school freshman who plays on the football team.
As a seventh grader, Alex was subjected to the taunting and pushing that seems to be commonplace in schools throughout the United States. Then, in eighth grade, the roles changed. Alex was no longer the victim but the aggressor.
"It felt great," said Alex, adding that being a bully gave him a sense of strength and leadership.
"You taste that powerful feeling of being the one in control. It's very exciting," Saltz explained. "And you can really lose your moral compass."
Alex and his friends were involved in multiple bullying incidents that were never brought to the attention of school officials, mainly because the student victims were afraid of reprisals.
Then, in January, the bullied students told the principal. The boys were set to be expelled, but they were suspended instead and put in a mandatory six-week group counseling intervention program. There was no official anti-bullying program in place, but the boys were required to create an anti-bullying presentation as part of the intervention. Alex said it gave him a chance to reflect on the cycle of violence and the best way to prevent it.
"It's a bullying cycle. You want to get revenge, and that's why we created the program to stop the bullying before it starts," said Alex.
Alisha, who spent time in foster care, said she wanted to take out her anger on others.
"I would tease kids in class, in the hallways. I was more of a mental bully instead of a physical bully," Alisha told ABC News. "If somebody would actually try to get smart back with me, I would probably take it to a fighting level."
The cruelest room in the school was the lunchroom. "That's where ... kids bully people. There's the cool kids, the smart kids, the weird kids and everyone sits at different tables and bust on each other, which is slang for make fun. How you acted really was defining if you were gonna get picked on or not," she said.
Ultimately, Alisha decided to reform her ways. She said she hoped a nicer Alisha could serve as a role model for her younger sister and brother.
Saltz said bullies come in all shapes and sizes, but a common thread is that they haven't been taught empathy.
"You know, kids who aren't getting a message that being good and kind and empathetic count, hugely," Saltz said.
"Many kids who are bullying today are actually quite confident. They are athletes, they are attractive, they are academically high performers," Saltz said. "It's not as simple as this dynamic of, you know, I'm failing so I need to get more so I take it out on somebody else."
As with bullies, bullying takes many forms. "A lot of kids don't understand, for instance, that being shunned and left out, although not overtly tortured, is bullying," Saltz said.
Along with strict anti-bullying policies, education is the best approach to end the behavior, she said.
"A lot of it has to do with education, changing the culture. It's not cool to be a bully," Saltz said. "We're not gonna let it happen."
"The Bully Project" is an independent documentary that highlights kids and families across the United States through the school year as they deal with bullying. Their website offers advice on how to get help if you're a victim of bullying and how to donate to the project. Click here to learn more about "The Bully Project."