Arelys Madero-Hernandez & Carlos E. Rojas-Gaona, Criminal Justice, presented a paper at the Academy of Criminal Justice Sciences (ACJS) Annual Meeting entitled “Collective Efficacy and Crime: Exploring the Longitudinal Mechanisms in Los Angeles, 2000-2008.” This is a state-of-the-art study addressing the longitudinal effects of collective efficacy on crime, more specifically, the impact of collective efficacy on community rates of robbery, youth victimization, and youth delinquency over time.