On Tuesday, a high-school student grasped a microphone and shared a painful memory of unrelenting bullying with the audience gathered in Matthews Arena: “I was walking down the hallway, and someone called me a terrible name. This time, I didn’t even hear it — I wasn’t paying attention — but it seems everybody else in the hallway did. It’s something that never stops hurting.”

Then, from deep in the crowd, a voice cried out “We love you!” and the nearly 4,000 middle- and high-school students who packed the arena erupted in cheers and applause. That sentiment of support was common throughout the daylong 2011 Stand Up conference hosted by Northeastern University, which drew students from across Massachusetts to discuss youth bullying.

The conference was created to educate, motivate and empower young people to actively promote positive social change in their schools and communities, and included remarks from state politicians and radio personalities. Students from Bridgewater State University also moderated a town hall-style dialogue.

Students shared their thoughts and experiences from microphones in the crowd and by answering poll questions on cell phone, with updates posted live on screens.

“I am so inspired to be here today to see all the great faces committed to this cause and this movement,” said Northeastern Athletics Director Peter Roby, one of the conference’s co-chairs. “The work you’ve done in your schools and your communities has been to make everyone feel welcome, and I hope that’s the spirit you carry back to your schools and your communities when you leave here today.”

The event included appearances by several local musicians, including American Idol finalist Siobhan Magnus, a Bridgewater, Mass., native, and public officials such as Attorney General Martha Coakley, whose office has pushed for tougher bullying legislation in Massachusetts.

“I know everyone tells you this, but you really are the ones who make a difference,” Coakley said. “Whether you choose to step in to help someone in need or choose to be a bystander and ignore the problem, you are making a difference, for better or worse.”

Elizabeth Englander, the director of the Massachusetts Aggression Reduction Center who cochaired the event with Roby, told students that even small actions to stop bullying could have monumental outcomes. She told the story of the Pink Shirt Campaign, which started simply as a way two seniors hoped to stop bullying at their high school.

“We want to help you, but you’re the ones who are going to make this happen, who are going to stop bullying. This is all about you,” Englander said.