Knife crime in Northern Ireland had increased from 81 incidents in May 2005 to 125 in May 2006. This paper reveals how the Police Service of Northern Ireland (PSNI) commissioned Genesis to create a campaign that would impact on those who were most likely to carry knives, 11 - 18-year-old males. Working collaboratively with the PSNI, the Juvenile Justice Bureau and the Youth Offending Team, Genesis spent time with this notoriously difficult and hard-to-reach audience, gaining insights into their motivations and beliefs. From this research they developed the campaign's advertising idea 'One thing can lead to another. NEVER carry a knife'. The campaign resulted in a 16.7% reduction in knife crimes, saving lives across Northern Ireland