Background <p>Gang-related activity and violence involving youths is an ongoing concern in the province of British Columbia, Canada. End Gang Life is a single session school-based gang awareness program developed and delivered by police officers.</p> Objectives <p> The objectives of the study are to examine the impact of program exposure on gang-related beliefs and knowledge about gang myths.</p> Methods <p> A prospective five-group quasi-experimental design was implemented in seven high schools. Schools were assigned to conditions including: (1) police officer single classroom presentations, (2) police officer large assembly presentations, (3) police officer and former gang member large assembly presentations, (4) poster display, and (5) waitlist control. Data were collected from 781 youth through self-report surveys before and after program implementation. The analytic strategy included multiple imputation, propensity score matching, and multilevel models.</p> Results <p>All three presentation groups showed statistically significant improvements in gang-related beliefs and knowledge relative to the control group. With respect to gang myths, students in the classroom presentation condition demonstrated the strongest gains in knowledge; for gang-related beliefs both the classroom condition and the former gang member assembly condition showed stronger effects relative to the police officer assembly group. No differences were found for either outcome between the poster-only condition and the control group.</p> Conclusions <p> The End Gang Life program is a promising approach to educating youths about the dangers and realities of gangs; specifically, presentations help students understand the myths and realities of gang life, and reduce pro-gang beliefs and participation in gang-related activities.</p>