Throughout the 1990s many countries around the world experienced the beginnings of what would later become the most significant and protracted decline in crime ever recorded. Although not a universal experience, the so-called international crime-drop was an unpredicted and unprecedented event which now offers fertile ground for reflection on many of criminology's key theories and debates. Through the lens of developmental and life-course criminology, this Element compares the criminal offending trajectories of two Australian birth cohorts born ten years apart in 1984 and 1994. It finds that the crime-drop was unlikely the result of any significant change in the prevalence or persistence of early-onset and chronic offending, but the disproportionate disappearance of their low-rate, adolescent-onset peers. Despite decades of research that has prioritized interventions for at-risk chronic offenders, it seems our greatest global crime prevention achievement to date was in reducing the prevalence of criminal offending in the general population.