In the wake of a mass shooting on October 1 in Las Vegas that left at least 59 people dead and more than 500 injured, David Hemenway, professor of health policy at Harvard T.H. Chan School of Public Health and director of the Harvard Injury Control Research Center, speaks with us about the public health approach to gun control. Hemenway discusses what made the Las Vegas shooting so deadly, how Australia effectively responded to a mass killing in 1996, and why restrictions on federally funded gun research hamper efforts to prevent violence. We also re-play a story on background checks and gun purchases from January, 2017.