'People who do nothing make it much worse'.
A crackdown on bullying will see victims, celebrities, politicians and experts unite to address the issue.
Bullying victim turned campaigner Gemma Lang, 22, from Caerphilly, will help Radio One Surgery presenter Kelly Osbourne take calls from listeners affected by the problem on tomorrow's show.
The programme comes ahead of Anti-Bullying Week, which starts on Monday, when politicians, researchers and other experts will unite for a conference on the subject in Cardiff.
The event, one of many planned UK-wide, will discuss a report by Barnardo's Cymru calling for more action to be directed towards passers-by and friends of bullies who turn a blind eye to abuse.
Gemma, who was bullied as a child, said: "Often the person who stands by and does nothing is the person who makes it feel worse. They quantify what the bully does as OK so it makes you feel more alone.
"But a lot of people are frightened of saying something because they worry about what might happen if they intervene."
Gemma, who runs her own anti-bullying website, has reported being verbally and emotionally abused in school as well as being kicked, punched, hit with sticks and threatened with a compass and a knife by attackers.
She is now an anti-bullying spokeswoman for the NSPCC and ChildLine as well as running her own campaign, Full Stop 2 Bullying.
The trainee probation officer is looking forward to the challenge of advising BBC Radio One listeners from the London studio.
She said: "Having a celebrity like Kelly Osbourne talking about bullying is great because young people identify with her.
"It's important to keep the campaign young and fresh because bullying is always changing.
"These days children have no respite at all because they can be contacted by the internet and mobile phone constantly. In the last few years there has been an increase in suicide and I'm sure that's why."
A new study by Barnardo's, for which 77 black and ethnic minority young people in Cardiff were interviewed, found that almost all reported bullying at school.
Half said they had also experienced bullying in the wider community.
The charity's research and policy officer Vikki Butler said the investigations showed more needed to be done to target friends of bullies who act as "back-up" to the ring leaders and passers-by who feel too intimidated by gangs to step in.
She said: "Changing the way in which the 'back-ups' and the witnesses think about bullying could help reduce incidences."
For details visit www.fullstop2bullying.co.uk
The Radio One Surgery starts at 10pm tomorrow.